Can anyone help me solve this question

Goal = 45 (expected mean per week)

Ice creams sold each day = 54,45,33,39,48,40,21

Total Ice creams sold = 54+45+33+39+48+40+21 = 280

Total number of observations = 7

Mean = Total sum/total number of observation

= 280/7 (on simplification) = 40

Expected goal = 45

Mean of ice creams actually sold = 40

More ice creams to sell = Expected goal - Mean of ice creams actually sold

(on substituting the values)

= 45-40

Thus , the answer is option D , which is 5.

i assume that by 5 you mean 5 gallons.

(20)(0.25) = 15

removing 15 gallons reduces the tank from 20 to 5.