Answer:
The calculated value of z= 2.7225 falls in the critical region therefore we reject the null hypothesis and conclude that at the 5% significance level, true proportion of correct responses to the question without context exceeds that for the one with context.
Step-by-step explanation:
a: 15 % of 1000= 150
b. 15.96 % of $ 1000= $ 159.6
The customer would pay = $ 1000- $ 159.6= $ 840.4 and save $ 159.6
Formulate the hypotheses as
H0: p1= p2 true proportion of correct responses to the question without context is equal that for the one with context.
Ha : p1≠ p2
We choose the significance level ∝= 0.05
The critical value for two tailed test at alpha=0.05 is ± 1.96
The test statistic is
Z = p1-p2/ √pq (1/n1+ 1/n2)
p1= true proportion students who answered the question without context correctly = 165/200=0.825
p2= true proportion of students who answered the question with context correctly = 142/200= 0.71
p = an estimate of the common rate on the assumption that the two proportions are same.
p = n1p1+ n2p2/ n1 + n2
p =200 (0.825) + 200 (0.71) / 400
p= 165+ 142/400= 307 /400 =0.7675
now q = 1-p= 1- 0.7675= 0.2325
Thus
z= 0.825- 0.71/ √0.7675*0.2325( 1/200 + 1/200)
z= 0.115/√ 0.17844( 2/200)
z= 0.115/0.04224
z= 2.7225
The calculated value of z falls in the critical region therefore we reject the null hypothesis and conclude that at the 5% significance level, true proportion of correct responses to the question without context exceeds that for the one with context.
