The average cost of 5 books is $80.
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 5 books
= 5 x 80
= $400
Number of books
= 5 + 2
= 7
Total cost of all the books
= 7 x 70
= $490
Total cost of the 2 books that are added
= 490 - 400
= $90
(b)
Average cost of the 2 books that are added
= 90 ÷ 2
= $45
Answer(s): (a) $90; (b) $45