Hypothesis Testing 3A

11.) A random sample of 1,600 adults in a certain country shows that 72% have smart phones. What is a 80% confidence interval for the percentage of adults having smart phones in this country?
a. 72%±1.85% b. 72%±1.44% c.72%±2.24% d.72%±1.11%

12.If 48% of the 400 voters sampled voted for candidate A over candidate B, what is a 95% confidence for p hat, the estimate for the percentage candidate p that A would receive?
a. 48%±2.5% b. 48%±5% 48%±10% d. 48%±1%

13.Twenty-five randomly selected students are asked how many times a month they eat pizza. The average for this sample is x̅25= 11.75 times, but the population mean of all college students is claimed to be μ = 10.60 times. If the null hypothesis is H0 is μ = 10.60 times and the standard deviation σ = 5 times, should the null hypothesis be rejected at the 5% level of significance? (No table needed)
a. Yes b. No c. Not enough information

14. Is the distribution of incomes in the US described by a normal distribution with μ equal to the mean income?
a. Yes b. No c. Not enough information

15. The weights of baby orangutans has standard deviation 4 pounds. How large a sample of baby orangutans is necessary for the 95% margin of error to be .5 pounds?
a. 144 b. 324 c. 256 d. 900

16. A car manufacturer says their cars average 26 miles per gallon of gas at 65 miles per hour a standard deviation of σ = 2 miles per gallon.. A Consumer group tested 100 such cars and found the average x̅100 to be 25.4 miles per gallon. Is this sufficiently small to reject the null hypothesis H0: μ = 26 miles per gallon? (No table needed.)
a. Yes b. No c. Not enough information.

17. What is the probability that z, the standard normal distribution, is less than 1.75 standard deviations below the mean of zero?
a. 5% b. 4% c. 6% d. 7.4%

18. If two random samples of the heights of adult males in New York are taken, one of 400, the other of 900 people, which one would likely have the larger range from shortest to tallest?
a. the 400 person sample b. the 900 person sample c. they'd be equal

19. The p-value of a test of the null hypothesis is 3.5%. This means
a. the hypothesis is true with probability 3.5% or possibly less than 3.5% b. the alternative hypothesis is true with probability 3.5% or possibly less c. 3.5% is the probability of finding the observed or more extreme results when the null hypothesis (H 0) is true d. None of the above

20. One of the main reasons to be interested in the regression line of y on x is that
a. one can use it to predict y-values from different x-values b. one can determine the standard deviation of y
c. one can determine from it the values of the quartiles of x and y.