Question

In Exercises 9–12, refer to the exercise identified. Make subjective estimates to decide whether results are significantly low or significantly high, then state a conclusion about the original claim. For example, if the claim is that a coin favours heads and sample results consist of 11 heads in 20 flips, conclude that there is not sufficient evidence to support the claim that the coin favours heads (because it is easy to get 11 heads in 20 flips by chance with a fair coin).

Exercise 6 “Cell Phone”

Short answer

The result of 95% of adults who have cell phonesseems significantly low.

There is sufficient evidence to support the claim that the proportion of adults who have a cell phone is less than 95%.

Step-by-step solution

Given information

Referring to Exercise 6, out of 1128 adults, 87% said they have a cell phone.

Conclusion

It is claimed that less than 95% of adults have a cell phone, that is, $p<0.95$.

Since 87% is considerably less than 95%, it appears to be unlikely to obtain a proportion of 87% in a sample when the true proportion is 95%.

Therefore, the result of 87% appears to be significantly low.

Thus, this suggests that there is evidence to support the given claim that the proportion of adults who have a cell phone is less than 95%.