The average cost of 5 books is $90.
After 2 new books are added,
the average cost of all the books is $80.
- What is the total cost of the 2 books that are added?
- What is the average cost of the 2 books that are added?
(a)
Total cost of 5 books
= 5 x 90
= $450
Number of books
= 5 + 2
= 7
Total cost of all the books
= 7 x 80
= $560
Total cost of the 2 books that are added
= 560 - 450
= $110
(b)
Average cost of the 2 books that are added
= 110 ÷ 2
= $55
Answer(s): (a) $110; (b) $55