Question

A manufacturer claims his light bulbs have a mean life of 1800 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 230 bulbs and found them to have a sample mean life of 1790 hours and a sample standard deviation of 50 hours. Assess the manufacturer's claim. a) What is the null hypothesis? 正确:D=1800 错误x = 1800 错误x<1800 错误p> 1800 正确答案! 以前的尝试 您的证明编号是153-43332 b) What is the alternative hypothesis? 错误 > 1800 错误文< 1800 错误 > 1800 正确:p< 1800 正确答案! 您的证明编号是153-11700 以前的尝试 c) Give the value of the test statistic, to two places past the decimal point. 提交答案 Tries 0/5 d) What is the significance probability or P value. Choose the appropriate range. 错误P>.10 错误.05 <P<.10 错误.01(P<.05 正确:P<.01 正确答案! 您的证明编号是153-76980 以前的尝试 e) Are the results statistically significant at the .05 level of significance? 正确:Yes 错误 No 正确答案! 「以前的尝试 您的证明编号是153-85036

Answer 1

c) Test statistic

$\small t = \frac{1790-1800}{50/\sqrt{230}}$

= -3.03