Answer
90.
Work Step by Step
By using the table, the z-score belonging to the area 0.25: z=-0.667. $IQ=mean+z\cdot(standard \ deviation)=100+(-0.667) \cdot 15=100+(-10)=90.$
Essentials of Statistics (5th Edition)
by Triola, Mario F.
Published by
Pearson
ISBN 10:
0-32192-459-2
ISBN 13:
978-0-32192-459-9
Chapter 6 - Normal Probability Distributions - 6-3 Applications of Normal Distributions - Page 262: 18
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