Question

An IRS report stated that 17% of all electronically filed income tax returns for 2003 contained errors.  H&R Block suspects this percentage has changed.  In a random sample of 250 electronically filed income tax returns for 2003, 35 were found to contain errors.

(a) What is the test statistic?

(b) Is there evidence to indicate that this proportion has changed? if so,

a.

Yes, the p-value is greater than 0.05.

b.

No, the p-value is less than 0.05.

c.

Yes, the p-value is less than 0.05.

d.

No, the p-value is greater than 0.05.

thanks for any help that can be given!

Answer 1

null Hypothesis:              Ho:   p=		0.170
alternate Hypothesis:    Ha: p ≠		0.170

sample success x   =		35
sample size          n    =		250
std error σp =√(p*(1-p)/n) =		0.0238
sample prop p̂ = x/n=35/250=		0.1400
z =(p̂-p)/σp=(0.14-0.17)/0.024=		-1.26

(please try -1.2628 if z score required for more than 2 decimals)

b)

option D is correct

No, the p-value is greater than 0.05.