Which industry had the greatest percentage increase in profits as a percentage of sales between 1966 and 1974? what was the percentage increase (to the nearest tenth)?

Petroleum = 15.32%

Drugs = 12.9%

Chemicals = 2.5%

Motor Vehicles =  -56.5% (Negative)

Electrical =  -18.8% (Negative)

Food = 3.7%

Step-by-step explanation

Here we have to use the formula to find the percentage of increase.

Percentage of increase = Increased amount / original amount * 100

Let's find the percentage of increase of each firm from 1966 and 1974

Petroleum = ((12.8 - 11.1) ÷ 11.1)) *100 = (1.7 ÷ 11.1)*100 = 15.32%

Drugs = ((12.2 - 10.8) ÷ 10.8)) *100 = (1.4 ÷ 10.8)*100 = 12.9%

Chemicals = ((8.2 - 8) ÷ 8)*100 = (0.2 ÷ 8)*100 = 2.5%

Motor Vehicles = ((2.7 - 6.2)÷6.2)*100 = (-3.5÷6.2)*100 = -56.5% (Negative)

Electrical =  ((3.9 - 4.8)÷4.8)*100 = (-0.9÷4.8)*100 = -18.8% (Negative)

Food = ((2.8-2.7)÷2.7))*100 = (0.1 ÷2.7)*100 = 3.7%

Hope you will understand the concept.

Thank you.