The average cost of 8 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 8 books
= 8 x 90
= $720
Number of books
= 8 + 2
= 10
Total cost of all the books
= 10 x 80
= $800
Total cost of the 2 books that are added
= 800 - 720
= $80
(b)
Average cost of the 2 books that are added
= 80 ÷ 2
= $40
Answer(s): (a) $80; (b) $40