The average cost of 4 textbooks is $20.
After another textbook that costs $70 is added,
- What is new total cost of all the textbooks?
- What is new average cost of all the textbooks?
(a)
Total cost of 4 textbooks
= 4 x 20
= $80
New total cost of all the textbooks
= 80 + 70
= $150
(b)
New total number of textbooks
= 4 + 1
= 5
New average cost of all the textbooks
= 150 ÷ 5
= $30
Answer(s): (a) $150; (b) $30