Answer:
The least possible score Pia can earn on the fourth assignment and still be able to finish the week with an average score of 90 on all five assignments is 86
Explanation:
The information given are;
Pia's scores in the first three assignments = 87, 85, and 92
The question asks to find upon finishing the week's five assignments the least possible score that Pia can earn on the fourth assignment and still be able to have an average score of 90 on all five assignments
Let the least score required to have an average score of 90 on all five assignments be X
If X is the least score to obtain an average of 90 for the five assignments, then fifth assignment score, will be maximum possible score obtainable to allow the attainment of the average score of 90 which is 100, which gives;
(87 + 85 + 92 + X + 100)/5 = 90
∴ 5 × 90 = 450 = 87 + 85 + 92 + X + 100 = 364 + X
X = 450 - 364 = 86
Therefore, the least possible score Pia can earn on the fourth assignment and still be able to finish the week with an average score of 90 on all five assignments = 86.