Question

In 2017 at a mechanic’s shop 35% of customers needed wheel or brake repairs, 40% needed engine repairs, 10% needed bodywork repairs, 10% needed electrical repairs, and 5% needed interior repairs. The mechanic wants to know if those proportions are still accurate in 2020. He randomly selects 90 repairs performed so far in 2020 and finds the following data. Type of repair Wheel/Brake Engine Bodywork Electical Interior Count 23 47 7 11 2 Have the proportions of repairs changed from the 2017 values? Test using α = 0.05.

Answer 1

for p value using excel formula =CHISQ.DIST.RT(7.93,4)