You are interested in determining which of two brands of light bulbs, brand A and brand B, lasts longer under differing conditions of use. Fifty Bovano lamps are fitted with brand A light bulbs, and 50 Bulbrite lamps are fitted with brand B light bulbs. Each light bulb is left on for 20,000 hours straight. Light bulb life is then measured for each bulb, and the average light bulb life for the two brands is compared. What is wrong with this experimental design? Nothing is wrong with this design. The type of lamp is a confounding variable. Not enough light bulbs of each type are used in the study. The experiment should have been conducted on more than two brands of lam

You are interested in determining which of two brands of light bulbs, brand A and brand B, lasts longer under differing conditions of use. Fifty Bovano lamps are fitted with brand A light bulbs, and 50 Bulbrite lamps are fitted with brand B light bulbs. Each light bulb is left on for 20,000 hours straight. Light bulb life is then measured for each bulb, and the average light bulb life for the two brands is compared. What is wrong with this experimental design? Nothing is wrong with this design. The type of lamp is a confounding variable. Not enough light bulbs of each type are used in the study. The experiment should have been conducted on more than two brands of lam

A First Course in Probability (10th Edition)

10th Edition

ISBN:9780134753119

Author:Sheldon Ross

Publisher:Sheldon Ross

Chapter1: Combinatorial Analysis

Section: Chapter Questions

Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...

See similar textbooks

Similar questions

Can balloons hold more air or more water before bursting? A student purchased a large bag of 12-inch balloons. He randomly selected 10 balloons from the bag and then randomly assigned half of them to be filled with air until bursting and the other half to be filled with water until bursting. He used devices to measure the amount of air and water was dispensed until the balloons burst. Here are the data
You are a researcher who wants to know what the mean (µ) level of anxiety would be for the whole population if they were all receiving a new anti-anxiety therapy. You can’t give the therapy to the whole population, so you give it to a sample, and you get M = 32.1 as the average anxiety level for the sample on the therapy. What is the reason that you can’t just simply assume that µ = 32.1? You didn’t use random assignment Sampling error Descriptive statistics Inferential statistics
Shelia’s doctor is concerned that she may suffer from gestational diabetes (high blood glucose levels during pregnancy). There is variation both in the actual glucose level and in the blood test that measures the level. A patient is classified as having gestational diabetes if her glucose level is above 136 milligrams per deciliter (mg/dl) one hour after ingesting a sugary drink. Shelia’s measured glucose level one hour after the sugary drink varies according to the Normal distribution with μ = 125 mg/dl and σ = 11 mg/dl. a)What are the mean and standard deviation of the distribution of sample proportion if measurements are made instead on 40 separate days? b)If measurements are made on 40 separate days and the mean result is compared with the criterion 140 mg/dl, what is the probability that Shelia is diagnosed as having gestational diabetes? c)Let’s consider what could happen if we took 40 separate measurements from Shelia. What is the blood glucose level L such that the probability…
In North America, between 100 million and 1 billion birds die each year by crashing into windows on buildings, more than any other human-related cause. This figure represents up to 5% of all birds in the area. One possible solution is to construct windows angled downward slightly so that they reflect the ground rather than an image of the sky to a flying bird. An experiment by Klem et al. (2004) compared the number of birds that died as a result of vertical windows, windows angled 20 degrees off vertical, and windows angled 40 degrees off vertical. The angles were randomly assigned with equal probability to six windows and changed daily; assume for this exercise that windows and window locations were identical in every respect except angle. Over the course of the experiment, 30 birds were killed by windows in the vertical orientation, 15 were killed by windows set at 20 degrees off vertical, and 8 were killed by windows set at 40 degrees off vertical. a. Clearly state an appropriate…
A car company conducts crash tests of its new airbag system to evaluate its safety. One hundred cars are run into a solid concrete barrier at a speed of 35 miles per hour, and the chest compression of a crash test dummy is measured each time. They hope that the average compression if the test were repeated over and over (which we could think of as the population) would be about 2 inches, corresponding to an injury that would be painful but not fatal. In the hundred tests, the average chest compression in the crash test dummies was 2.1 inches, with an SD of 0.2 inches.(a) State the null and alternative hypotheses in terms of the problem.(b) What kind of box model will we use for this problem? A 0-1 box, or a box with other values on the tickets?(c) State the null and alternative hypotheses in terms of the box model (d) Compute the z test statistic and the p-value, using the sample average as your statistic as you compute z (e) What do you conclude?
The temperature of a certain chemical process is thought to be related to the time it takes for the process to reach completion. Out goal is to that relationship so that we can use it to predict TIME TO REACH COMPLETION at various TEMPERATURES. 14 trials are set up and the time for the process to complete is measured for each of the different temperatures. The data is presented here:(data is in the image added to the question as well as more questions to answer)
Some commercial airlines recirculate about half the air in the cabin during flights as a way to improve fuel efficiency. Other airlines make a policy of NOT recirculating the air and instead, have fresh air from the atmosphere constantly being inserted into the cabin with the “old” air being pumped out of the plane. A total of 1100 passengers flying from San Francisco to Denver were used for an experiment. After their flight, they were each given a list of symptoms associated with the common cold. They were asked to report if they experienced cold symptoms within 24 hours of the flight landing. Of the 517 passengers who flew on planes that recirculate the air, 108 reported post-flight cold symptoms. Of the 583 passengers who flew on airlines that do not use recirculation in the cabin, 110 reported symptoms. Suppose now that we want to use the recirculation of air data to explore “Goal #2”, which is to resolve a hypothesis test about . a) If we want to resolve this hypothesis…
man loves, as everyone should, to collect and analyze statistical information. He wishes to find a relationship between how many hours students study and how they do on their statistics tests. He takes a random sample of 16 students at Ideal U., asks how many hours they studied for a university-wide stat test and how they did on the test, enters the data into a computer for analysis and presents the results below. ANALYSIS OF HOURS AND GRADES (n = 16): Descriptive Statistics: HOURS GRADES Mean: 4.2 75.8 Mode: 5.0 79.0 St. Dev: 2.3 10.1 Quartiles: Q0 2.0 34.0 Q1 3.2 53.7 Q2 4.7 78.5 Q3 6.3 86.9 Q4 9.0 97.0 Regression Analysis: Reg. Eq. is: GRADE = 16.9 + 9.025*HOURS Rsquared = .985 std error = 0.027 F = 8.52 p = .018 What problem might there be in using the regression model to predict what grade a student might get if they studied 10 hours? a. The predicted grade for 10 hours is more than 100, which is impossible. b. The value of 10…
A study was developed to evaluate effectiveness of a weight loss diet plan. An ad was placed in two towns to locate study participants who were to follow the diet. In Town A, the clinicians asked each dieter to report how much weight they had lost over the previous 6 weeks while following the diet. In Town B, the clinicians weighed each dieter at the beginning of the study and again after 6 weeks on the diet program. The weight lost was calculated as the difference between the beginning weight and the weight after 6 weeks. At the end of the study, it was determined that Town B had lost significantly less weight than Town A. 1.What is the population of interest in this situation? 2. Identify source(s) of bias in this study.
Can a person train to become better at holding their breath? An experiment was designed to find out. Twelve volunteers were randomly assigned to 1 of 2 groups. The 6 volunteers assigned to group 1 were given breath-holding exercises to perform for 2 weeks. The other group was not given any information about the experiment. At the end of the 2 weeks, all 12 volunteers were individually tested to determine how long they could hold their breath. Here are the data (in seconds). Group 1: 90, 88, 70, 110, 75, 105 Group 2: 40, 48, 35, 50, 55, 62 The researcher would like to determine if these data provide convincing evidence that the true mean amount of time volunteers who were given training held their breath is greater than volunteers without training. Let ₁ = the true mean amount of time that volunteers who were given training held their breath and ₂ = the true mean amount of time that volunteers without training held their breath. What are the appropriate hypotheses? Ho: U1 - U2 = 0, Ha:…
A researcher is interested in hamster wheel-running activity during the summer versus the winter. She suspects that either the hamsters will run less during the winter to conserve energy or they will run more to keep warm. She records the activity of n = 25 hamsters during June, July, and August and compares their running-wheel revolutions per hour to the activity of the same hamsters during December, January, and February. The data are collected, and the results show an average difference score of MD - 5.7 and a sum of squares of SS = 2,851.44. What is the sample standard deviation (s) for the D scores? (one decimal)
An outbreak of the deadly Ebola virus in 2002 and 2003 killed 91 of the 95 gorillas in 7 home ranges in the Congo. To study the spread of the virus, measure " distance" by the number of home ranges separating a group of gorillas from the first group infected. Here are data on distance and number of days until deaths began in each later group: Distance xx 2 5 4 4 4 6 Days yy 4 21 29 40 47 49 Use a calculator or software to find the following values. (a) Find the mean and standard deviation of xx. MEAN: STANDARD DEVIATION: (b) Find the mean and standard deviation of yy. MEAN: STANDARD DEVIATION: (c) Find the correlation rr between xx and yy. r: