Question

Proctor & Gamble claims that at least half the bars of Ivory soap they produce are 99.44% pure (or more pure) as advertised. Unilever, one of Proctor & Gamble's competitors, wishes to put this claim to the test. They sample the purity of 146 bars of Ivory soap. They find that 61 of them meet the 99.44% purity advertised.

What type of test should be run?

a. t-test of a mean

b. z-test of a proportion

The alternative hypothesis indicates

a. a left-tailed test

b. two-tailed test right-tailed test

Calculate the p-value.

Does Unilever have sufficient evidence to reject Proctor & Gamble's claim?

a. No b.Yes

Answer 1

The statistical software output for this problem is:

We need to test for a single proportion in this case. So, we will use z test of a proportion.

The alternative hypothesis indicates a left-tailed test

p - Value = 0.0235

Does Unilever have sufficient evidence to reject Proctor & Gamble's claim?

Yes