Question

Question 7: At Rachel’s 21th birthday party, 16 girls were timed to see how long (in seconds) they could hold their breath in a relaxed position. After a two-minute rest, they timed themselves while jumping. The sample mean and variance of the difference between their jumping and relaxed times is -3.2 (Jumping minus relaxed) and 9.2342 .The girls thought that the mean difference between their jumping and relaxed times would be zero.

a) Is this an observational study or an experiment?

b) Identify (and classify) the explanatory and response variables.

c) Perform a hypothesis test by using the statistical process at a significance level of 0.01. You do not have to visualize the assumptions or the data for this question.

Answer 1

a) Is this an observational study or an experiment?

Ans - This is an observational study as it is carried out by observations

b) Identify (and classify) the explanatory and response variables

Ans - Response variable - mean difference between their jumping and relaxed times would be zero

c) Perform a hypothesis test by using the statistical process at a significance level

Ans - '

H0: mean difference between their jumping and relaxed times would be zero

H1: mean difference between their jumping and relaxed times would be not zero

t-statistic	1.386
DF	15
Significance level	0.01
p- value	0.18600

As p-value > 0.01, we accept the null hypothesis

Hence we can conclude that,

mean difference between their jumping and relaxed times would be zero