Answer:
Chemical industry had the greatest percentage increase in profits as a percentage of sales between 1970 and 1974 i.e. 64 %
Explanation:
Type firm : 1966 1970 1974
Petroleum 11.2 9.3 12.7
Drugs 10.8 9.4 12.2
Chemicals 8.0 5.0 8.2
Motor Vehicles 6.2 2.4 2.7
Electrical 4.8 3.3 3.9
Food 2.7 2.5 2.8
Now we need to check increase in percentage of sales between 1970 and 1974
Sale of petroleum in 1970 = 9.3
Sale of petroleum in 1974 = 12.7
So, increase = 12.7-9.3 =3.4
So, percentage of increase in petroleum =

=

=

Sale of drugs in 1970 = 9.4
Sale of drugs in 1974 = 12.2
So, increase = 12.2-9.4 =2.8
So, percentage of increase in drugs =

=

=

Sale of chemicals in 1970 = 5
Sale of chemicals in 1974 = 8.2
So, increase = 8.2-5 =3.2
So, percentage of increase in chemicals =

=

=

Sale of motor vehicles in 1970 = 2.4
Sale of motor vehicles in 1974 = 2.7
So, increase = 2.7-2.4 =0.3
So, percentage of increase in vehicles =

=

=

Sale of electrical in 1970 = 3.3
Sale of electrical in 1974 = 3.9
So, increase =3.9-3.3 =0.6
So, percentage of increase in electrical =

=

=

Sale of food in 1970 = 2.5
Sale of food in 1974 = 2.8
So, increase =2.8-2.5 =0.3
So, percentage of increase in food =

=

=

Chemical industry had the greatest percentage increase in profits as a percentage of sales between 1970 and 1974 i.e. 64 %