Curing times in days (x) and compressive strengths in MPa (V) were recorded for severalconcrete specimens. The means and standard deviations of the x and y values were* = 5, s, = 2, 5 = 1350, s, = 100. The correlation between curing time and compressivestrength was computed to be r = 0.7. Find the equation of the least-squares line to predictcompressive strength from curing time.

Introduction: A simple linear regression equation is of the form:

Answered: Curing times in days (x) and…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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A fuel company wants to find the functional relation between the amount of gas it sells for heating and the daily temperature. Given the values for 10 observations ∑x= - 50, ∑x^2 = 626, ∑y^2 = 6432 ∑y= 222, ∑xy= —1743 for the daily average temperature and gas sales (in thousand liters). a) Obtain and interpret the correlation coefficient for the variables.b) Set up the regression equation and interpret the coefficients.c) Find R2 and interpret.d) When the temperature is 10 degrees, please observe the gas sales amount.
A market study found that the sales for a firm were related to advertising expenditure, as follows: Advertising Expenditure (Kshs ‘000’) Sales (Kshs ‘000’) 0 13 1 16 2 14 3 22 4 17 5 21 6 26 Required Draw a scatter diagram with the line of best fit to show the relationship. Determine the regression line equation for estimating the sales for a given level of advertising expenditure What is the estimated sale in thousand, if no advertising expenditure is incurred?
What is the R2 value for the relationship between Height and Weight?
There is a relationship between the following variables as y = 1 / (a * x ^ b) (x ^ b: means x over b). a) Calculate the correlation coefficient and interpret the degree of the relationship? b) Estimate the y value for x = 4.3 and the x value for y = 0.90 by obtaining the regression equation. x 1.2 1.5 2.0 3.0 4.0 5.0 y 0.58 0.50 0.32 0.18 0.15 0.10 x 1.2 1.5 2.0 3.0 4.0 5.0 y 0.58 0.50 0.32 0.18 0.15 0.10
Please answer as many as your allowed too. Thank you :) A regression was run to determine if there is a relationship between the happiness index (y) and life expectancy in years of a given country (x).The results of the regression were: ˆyy^=a+bxa=-1.68b=0.168 (a) Write the equation of the Least Squares Regression line of the formˆyy^= + x(b) Which is a possible value for the correlation coefficient, rr? -1.417 1.417 0.702 -0.702 (c) If a country increases its life expectancy, the happiness index will increase decrease (d) If the life expectancy is increased by 0.5 years in a certain country, how much will the happiness index change? Round to two decimal places.(e) Use the regression line to predict the happiness index of a country with a life expectancy of 69 years. Round to two decimal places.
The article "The Undrained Strength of Some Thawed Permafrost Soils"+ contained the accompanying data on the following. y = shear strength of sandy soil (kPa) x₁ = depth (m) x₂ = water content (%) The predicted values and residuals were computed using the estimated regression equation y = -156.50 - 16.52x₁ + 13.83x₂ + 0.100x3 -0.258x4 +0.496x5 ₁², x₁ = x₂², and x5 = X1X2• where x3 = y X1 14.7 8.8 31.4 48.0 36.5 26.9 25.6 36.9 25.8 x2 10.0 6.2 39.2 16.0 6.8 39.3 20.7 16.8 7.0 38.4 7.4 33.8 38.8 8.3 33.9 16.9 6.4 27.0 8.1 33.2 24.9 10.0 12.8 28.0 16.0 4.4 26.2 37.9 7.3 2.8 34.7 1.9 36.5 Predicted y 22.86 46.10 27.38 11.23 13.47 16.80 23.55 25.24 15.75 24.47 15.19 29.93 15.51 8.00 Residual -8.16 1.90 -1.78 -1.23 2.53 0.00 -2.85 13.56 1.15 2.53 0.81 -5.03 -8.21 4.80 (a) Use the given information to calculate SSResid, SSTO, and SSRegr. (Round your answers to four decimal places.) SSTO = SSResid = SSRegr = (b) Calculate R² for this regression model. (Round your answer to three decimal…
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The individual residual scores from a sample of participants regarding the difference between the predicted Y values from a regression equation and the actual Y from the data are provided here. Y - Ŷ = 3,8,1,2,2. What is the value for the standard error of estimate?
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Below are bivariate data O each of twelve countries. For each of the countries, both x, the number of births per one thousand people in the population, and y, the female life expectancy (in years), are given. Also shown are the scatter plot for the data and the least-squares regression line. The equation for this line is ing birthrate and life expectancy information for y = 81.87 – 0.46x. Birthrate, x (number of births per 1000 pop.) Female life expectancy, y (in years) 85- 35.7 67.7 80- 41.5 63.9 75 31.9 63.3 19.9 73.0 70 50.5 60.4 65. 24.4 72.7 60- 50.1 63.2 55 13.8 72.5 50 50.3 54.6 45.6 57.9 15.9 76.2 Figure 1 26.6 71.9 Send data to Excel

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