The average cost of 4 books is $70.
After 2 new books are added,
the average cost of all the books is $50.
- 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 4 books
= 4 x 70
= $280
Number of books
= 4 + 2
= 6
Total cost of all the books
= 6 x 50
= $300
Total cost of the 2 books that are added
= 300 - 280
= $20
(b)
Average cost of the 2 books that are added
= 20 ÷ 2
= $10
Answer(s): (a) $20; (b) $10