The recommended daily dietary allowance for zinc among males

The recommended daily dietary allowance for zinc among males older than age 50 years is 15 mg/day. An article reports the following summary data on intake for a sample of males age 6574 years: n = 116, x = 12.2, and s = 6.57. Does this data indicate that average daily zinc intake in the population of all males age 6574 falls below the recommended allowance? (Use = 0.05.)
State the appropriate null and alternative hypotheses.

H₀: = 15
H_a: > 15H₀: = 15
H_a: < 15    H₀: = 15
H_a: 15H₀: = 15
H_a: 15

Calculate the test statistic and determine the P-value. (Round your test statistic to two decimal places and your P-value to four decimal places.)

Solution

the correct appropriate null and alternative hypotheses.

Ha: < 15    H0: = 15

Z- value = 12.2-15/(6.57/sqrt(116)) = -4.59

The P-value = 0.0000