Question 5

The first iPhone became available for public purchase in 2007. By 2010, approximately 30% of smartphone users in the United States owned an iPhone. Several new companies have entered the smartphone market since then and the folks at Apple want to know how they are stacking up against their competition. In 2019, a representative sample of 529 smartphone users in the United States showed that 47.4% use an Apple iOS device. Does Apple's share of the U.S. smartphone market appear to have increased since 2010?

The standardized test statistic for this study is 8.7. Select the best contextual interpretation of the test statistic.

a. The probability of obtaining a sample proportion of 0.474 or something more extreme, assuming 30% of all U.S. smartphone users use an Apple iOS device, is 8.7.

b. On average, each simulated proportion of the U.S. smartphone market which uses Apple iOS devices is 8.7 away from 0.299.

c. The proportion of the U.S. smartphone market that uses an Apple iOS device is 8.7.

d. The 0.474 proportion of the U.S. smartphone users sampled who use Apple iOS devices is 8.7 standard deviations above the 2010 Apple U.S. market-share of 0.30.