The average cost of 3 textbooks is $30.
After a textbook that costs $70 is removed,
- What is new total cost of all the remaining textbooks?
- What is new average cost of all the remaining textbooks?
(a)
Total cost of 3 textbooks
= 3 x 30
= $90
New total cost of all the remaining textbooks
= 90 - 70
= $20
(b)
Number of remaining textbooks
= 3 - 1
= 2
New average cost of all the remaining textbooks
= 20 ÷ 2
= $10
Answer(s): (a) $20; (b) $10