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 144 bars of Ivory soap. They find that 71 of them meet the 99.44% purity advertised.

What type of test should be run?

• z-test of a proportion
• t-test of a mean

The alternative hypothesis indicates a

• left-tailed test
• two-tailed test
• right-tailed test

Calculate the p-value.

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

• No
• Yes