Question

When people smoke, the nicotine they absorb is converted to cotinine, which can be measured. A sample of 70 smokers has a mean cotinine level of 172.3 ng/ml and a stadard deviation of 118.2 ng/ml. What is the value of the test statistic when testing the claim that the mean cotinine level of all smokers is less than 200.0 ng/ml at the significance level 5%?

Select one: a. -1.64 b. 1.64 c. None of the other answers is neccessary true. d. -1.96 e. 1.96

Answer 1

Solution,

The null and alternative hypothesis is ,

H0 :   = 200

Ha : < 200

= 172.3

= 118.2

n = 70

Test statistic = z =

= ( - ) / / n

= (172.3 - 200) / 118.2 / 70

Test statistic = z = -1.96

correct option is = d