Question

safety administration conducted crash tests of child booster seats for cars. Listed below are results from those tests, with the measurements given in hic (standard head injury condition units). The safety requirements is that the hic measurements should be less than 1000 hic. Use a 0.05 significance level to test the claim that the sample is from a population with a mean less than 1000 hic. Do the results suggest that all of the child booster seats meet the specified requirement? 622 617 1189 597 543 470

Answer 1

To test against

Here

sample mean

sample standard deviation

and sample size

The test statistic can be written as

which under H₀ follows a t distribution with n-1 df.

We reject H₀ at 0.05 significance level if P-value < 0.05

Now,

The value of the test statistic =

and P-value =

Since p-value <0.05, so we reject H₀ at 0.05 significance level and we can conclude that population mean is significantly less than 1000 hic.