Question

An important feature of tablets is battery life, the number of hours before a battery needs to be recharged. The accompanying data contains battery life information for 12 WiFi-only and 7 3G/4G/WiFi tablets. Complete parts (a) through (d) below. Click the icon to view the battery life data for the two types of tablets. a. Is there evidence of a difference in the variability of the battery life between the two types of tablets? (Use a = 0.10.) What are the correct null and alternative hypotheses? / 4G O A. Ho: WiFi only so 3G/4G Hy: oWiFi only > o3G/4G OC. Ho: O WiFi only # o 3G/4G Hy: oWiFi only = ožG/46 B. Ho: O WiFi only = 03G146 Hy : o WiFi only #ośc/ 46 O D. Ho:OWiFi only 20361 46 Hy: OWiFi only <ožG/4G What is the test statistic? FSTAT = 4.70 (Type an integer or a decimal. Round to two decimal places as needed.) What is the critical value? Select the correct choice below and fill in the answer box within your choice. (Type an integer or a decimal. Round to two decimal places as needed.) A. Fa/2=0 OB. Fa=

Answer 1

Ans a ) option B is true

$H0:\sigma _{wifi only}^{2}=\sigma _{3G/4G}^{2}$

$H0:\sigma _{wifi only}^{2}\neq\sigma _{3G/4G}^{2}$

using minitab>stat>basic stat> 2 variance

we have

Test and CI for Two Variances: Wifi Only, 3G/4G/WiFi

Method

Null hypothesis σ(Wifi Only) / σ(3G/4G/WiFi) = 1
Alternative hypothesis σ(Wifi Only) / σ(3G/4G/WiFi) ≠ 1
Significance level α = 0.05

F method was used. This method is accurate for normal data only.

Statistics

95% CI for
Variable N StDev Variance StDevs
Wifi Only 12 1.803 3.252 (1.277, 3.062)
3G/4G/WiFi 7 0.832 0.692 (0.536, 1.832)

Ratio of standard deviations = 2.167
Ratio of variances = 4.696

95% Confidence Intervals

CI for
CI for StDev Variance
Method Ratio Ratio
F (0.932, 4.269) (0.868, 18.225)

Tests

Test
Method DF1 DF2 Statistic P-Value
F 11 6 4.70 0.070

F_stat = 4.70

The critical value Fa/2 = 2.92