The average cost of 7 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 7 books
= 7 x 80
= $560
Number of books
= 7 + 2
= 9
Total cost of all the books
= 9 x 70
= $630
Total cost of the 2 books that are added
= 630 - 560
= $70
(b)
Average cost of the 2 books that are added
= 70 ÷ 2
= $35
Answer(s): (a) $70; (b) $35