The average cost of 6 books is $90.
After 2 new books are added,
the average cost of all the books is $70.
- 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 6 books
= 6 x 90
= $540
Number of books
= 6 + 2
= 8
Total cost of all the books
= 8 x 70
= $560
Total cost of the 2 books that are added
= 560 - 540
= $20
(b)
Average cost of the 2 books that are added
= 20 ÷ 2
= $10
Answer(s): (a) $20; (b) $10