McGraw Hill Integrated II, 2012
MH
McGraw Hill Integrated II, 2012 View details
5. Quadratic Inequalities
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Exercise 64 Page 213

Divide 116 with the given integers.

D

Practice makes perfect
We can look at the options one by one and try to find the other integer that falls outside the range by dividing 116 with the given numbers and taking the integer part of the result.
Option n 116/n Product Is it between 107 and 116?
A 5 116/5=23.2 23* 5=115 Yes
B 10 116/10=11.6 11* 10=110 Yes
C 12 116/12≈ 9.67 9* 12=108 Yes
D 15 116/15≈ 7.73 7* 15=105 No
E 23 116/23≈ 5.04 5* 23=115 Yes

We can see that for four of the numbers we could find a pair such that the product is between 107 and 116. The only number for which there is no such pair is 15. The correct answer is D.