Question 1177610
Assuming a random sample, normal distribution and sd of sample being a reasonable estimator of pop sd
t-test
Ho: rate of accidents = 0.075
Ha: it isn't
alpha=0.05= p{reject Ho| Ho true}

this is a t-test with df=139, critical value 1.98
t=(0.123-0.075)/0.167/sqrt(140)
=0.048*sqrt(140)/0.167
=3.40
reject Ho p-value is 0.0009