The average cost of 8 books is $90.
After 4 books are removed,
the average cost of the remaining books is $30.
- What is the total cost of the 4 books that are removed?
- What is the average cost of the 4 books that are removed?
(a)
Total cost of 8 books
= 8 x 90
= $720
Number of remaining books
= 8 - 4
= 4
Total cost of the remaining books
= 4 x 30
= $120
Total cost of the 4 books that are removed
= 720 - 120
= $600
(b)
Average cost of the 4 books that are removed
= 600 ÷ 4
= $150
Answer(s): (a) $600; (b) $150