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Concept explainers
E. Calculator Problems
You probably own a calculator and, of course, you are eager to put it to work doing practical math calculations. In this text we include problem sets for calculator users. These problems are taken from real-life situations and, unlike most textbook problems, involve big numbers and lots of calculations. If you think that having an electronic brain-in-a-box means that you do not need to know basic arithmetic, you will be disappointed. The calculator helps you to work faster, but it will not tell you what to do or how to do it.
Detailed instructions on using a calculator with whole numbers appears on page 68.
Here are a few helpful hints for calculator users:
- 1. Always estimate your answer before doing a calculation.
- 2. Check your answer by comparing it with the estimate or by the other methods shown in this text. Be certain that your answer makes sense.
- 3. If you doubt the calculator (they do break down, you know), put a problem in it whose answer you know, preferably a problem like the one you are solving.
Trades Management Joe’s Air Conditioning Installation Co. has not been successful, and he is wondering if he should sell it and move to a better location. During the first three months of the year, his expenses were as follows:
His monthly income was:
January $1760
February $2650
March $3325
- (a) What was his total expense for the three-month period?
- (b) What was his total income for the three-month period?
- (c) Now turn your calculator around to learn what Joe should do about this unhappy situation.
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Chapter 1 Solutions
EP MATHEMATICS FOR THE TRADES
- 2. Observations on the Wronskian. Suppose the functions y₁ and y2 are solutions to the differential equation p(x)y" + q(x)y' + r(x) y = 0 on an open interval I. 1. (a) Prove that if y₁ and y2 both vanish at the same point in I, then y₁ and y2 cannot form a fundamental set of solutions. 2. (b) Prove that if y₁ and y2 both attain a maximum or minimum at the same point in I, then y₁ and Y2 cannot form a fundamental set of solutions. 3. (c) show that the functions & and t² are linearly independent on the interval (−1, 1). Verify that both are solutions to the differential equation t² y″ – 2ty' + 2y = 0. Then justify why this does not contradict Abel's theorem. 4. (d) What can you conclude about the possibility that t and t² are solutions to the differential equation y" + q(x) y′ + r(x)y = 0?arrow_forwardThis exercise is based on the following data on four bodybuilding supplements. (Figures shown correspond to a single serving.) Creatine(grams) L-Glutamine(grams) BCAAs(grams) Cost($) Xtend(SciVation) 0 2.5 7 1.00 Gainz(MP Hardcore) 2 3 6 1.10 Strongevity(Bill Phillips) 2.5 1 0 1.20 Muscle Physique(EAS) 2 2 0 1.00 Your personal trainer suggests that you supplement with at least 10 grams of creatine, 39 grams of L-glutamine, and 90 grams of BCAAs each week. You are thinking of combining Xtend and Gainz to provide you with the required nutrients. How many servings of each should you combine to obtain a week's supply that meets your trainer's specifications at the least cost? (If an answer does not exist, enter DNE.) servings of xtend servings of gainzarrow_forwardPROBLEM 7: Binary Relations, Functions and Orderings (15 pts) 1. (2 pts) Prove that ({2, 3, 4, 6, 24, 36, 72}, /) is a poset, create its corresponding Hasse diagram and identify maximal and minimal elements. 2. (1 pts) Prove that (P{1, 2, 3}, C) is a poset, create its corresponding Hasse diagram and identify maximal and minimal elements 3. Assume the following mapping, captured by variable map: map = { 72 {1,2,3}, 36 {3}, 24 {1,2}, 6- → {3}, 4 {1,3}, 2➡ {} } Provide answers to the following in detail (in plain english and formally): (a) (2 pts) Is variable map a function? If so, is it a total or a partial function? Identify domain and codomain. (b) (10 pts) Discuss all properties (injectivity, surjectivity, bijection, order preserving, order reflecting, order embedding, isomorphism). NOTE: When we reason formally on a property we must state: (1) What Law do we expect to hold or not hold, and (2) Does this Law indeed hold or Is this Law violated?arrow_forward
- I need help with this problem and an explanation of the solution for the image described below. (Statistics: Engineering Probabilities)arrow_forwardI need help with this problem and an explanation of the solution for the image described below. (Statistics: Engineering Probabilities)arrow_forwardDATA TABLE VALUES Meal Price ($) 22.78 31.90 33.89 22.77 18.04 23.29 35.28 42.38 36.88 38.55 41.68 25.73 34.19 31.75 25.24 26.32 19.57 36.57 32.97 36.83 30.17 37.29 25.37 24.71 28.79 32.83 43.00 35.23 34.76 33.06 27.73 31.89 38.47 39.42 40.72 43.92 36.51 45.25 33.51 29.17 30.54 26.74 37.93arrow_forward
- I need help with this problem and an explanation of the solution for the image described below. (Statistics: Engineering Probabilities)arrow_forwardQuestion 4 Find an equation of (a) The plane through the point (2, 0, 1) and perpendicular to the line x = y=2-t, z=3+4t. 3t, (b) The plane through the point (3, −2, 8) and parallel to the plane z = x+y. (c) The plane that contains the line x = 1+t, y = 2 − t, z = 4 - 3t and is parallel to the plane 5x + 2y + z = 1. (d) The plane that passes through the point (1,2,3) and contains the line x = 3t, y = 1+t, and z = 2-t. (e) The plane that contains the lines L₁: x = 1 + t, y = 1 − t, z = 2t and L2 : x = 2 − s, y = s, z = 2.arrow_forwardPlease find all values of x.arrow_forward
- Sales personnel for Skillings Distributors submit weekly reports listing the customer contacts made during the week. A sample of 65 weekly reports showed a sample mean of 19.5 customer contacts per week. The sample standard deviation was 5.2. Provide 90% and 95% confidence intervals for the population mean number of weekly customer contacts for the sales personnel. 90% Confidence interval, to 2 decimals: ( , ) 95% Confidence interval, to 2 decimals:arrow_forwardA simple random sample of 40 items resulted in a sample mean of 25. The population standard deviation is 5. a. What is the standard error of the mean (to 2 decimals)? b. At 95% confidence, what is the margin of error (to 2 decimals)?arrow_forwardmean trough level of the population to be 3.7 micrograms/mL. The researcher conducts a study among 93 newly diagnosed arthritis patients and finds the mean trough to be 4.1 micrograms/mL with a standard deviation of 2.4 micrograms/mL. The researcher wants to test at the 5% level of significance if the trough is different than previously reported or not. Z statistics will be used. Complete Step 5 of hypothesis testing: Conclusion. State whether or not you would reject the null hypothesis and why. Also interpret what this means (i.e. is the mean trough different from 3.7 or noarrow_forward
- Algebra for College StudentsAlgebraISBN:9781285195780Author:Jerome E. Kaufmann, Karen L. SchwittersPublisher:Cengage LearningIntermediate AlgebraAlgebraISBN:9781285195728Author:Jerome E. Kaufmann, Karen L. SchwittersPublisher:Cengage Learning
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