Question

Question 4 A manufacturing company produces electrical insulators. If the insulators break when in use, short circuit is likely to occur. To test the strength of the insulators, destructive testing is carried out to determine how much force is required to break the insulators. Force is meas- ured by observing the number of pounds of force applied to the insulator before it breaks. In the Excel file provided "Data Assignment 2" there are the data from 30 insulators subjected to this testing. a) At the 0,05 level of significance, is there evidence that the population mean force is b) What assumption about the population distribution is needed in order to conduct the c) Construct an histogram or boxplot to evaluate the assumption made in b), and con- different than 1,5 pounds? t test in a)? clude. Store Shelf Space (X)(Feet) Weekly Sales(Y (S) 160 220 140 190 240 260 230 270 280 260 290 310 2 10 10 10 15 15 15 20 20 20 10 12

Answer 1

Two-Sample T-Test and CI: X, Y

Method

μ₁: mean of X

µ₂: mean of Y

Difference: μ₁ - µ₂

Equal variances are not assumed for this analysis.

Descriptive Statistics

Sample	N	Mean	StDev	SE Mean
X	12	12.50	5.84	1.7
Y	12	237.5	52.2	15

Estimation for Difference

Difference	95% CI for Difference
-225.0	(-258.4, -191.6)

Test

Null hypothesis	H₀: μ₁ - µ₂ = 1.5
Alternative hypothesis	H₁: μ₁ - µ₂ ≠ 1.5

T-Value	DF	P-Value
-14.93	11	0.000

Boxplot of X, Y

Boxplot of X, Y 350 300 250 200 150 100 50- 0-