Question

A manufacturer claims his light bulbs have a mean life of 2000 hours. A consumer group wants to test if their light bulbs do not last as long as the manufacturer claims. They tested a random sample of 210 bulbs and found them to have a sample mean life of 1980 hours and a sample standard deviation of 50 hours. Assess the manufacturer's claim. a) What is the null hypothesis? Ou = 2000 O x = 2000 Ox< 2000 Ou > 2000 A Tries 0/1 b) What is the alternative hypothesis? Ou > 2000 O X < 2000 OX > 2000 ON< 2000 B Tries 0/1 c) Give the value of the test statistic, to two places past the decimal point. A Tries 0/5 d) What is the significance probability or P value. Choose the appropriate range. OP>.10 0.05<P S. 10 0 .01 <P < .05 OP<.01 A Tries 0/2 e) Are the results statistically significant at the .05 level of significance? O Yes Ο Νο A Tries 0/1

Answer 1

a)

Ο μ = 2000

b)

Ο μ< 2000

c)

test statistic =(xbar-mean)*√n/standard deviation =(1980-2000)*sqrt(210)/50= -5.80

d)

OP<.01

e)

Yes