Work Step by Step
By using the table, the z-score belonging to the area 0.25: z=-0.667. $IQ=mean+z\cdot(standard \ deviation)=100+(-0.667) \cdot 15=100+(-10)=90.$
You can help us out by revising, improving and updating this answer.Update this answer
After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.