2. The Wehsler IQ test is normally distributed and has a known = 100 and a = 15. A sample of = 25 is drawn at random
	b. What middle range of sample IQs will be expected to occur 95% of the time?

Someone already answered and his answer is atttached here, Im just wondering where did the 1.96 came from and how to locate it.

From given information, XNN( = 100, 5 = 15) WKT X -y = Z ~ N10, JJ Therefore for middle 9501, data , We have P ( - 1 . 96 L Z ( 1 . 9 6 ) = 0.95 x - M = 1. 96 =) X - 100 = 1.96 - X= 129.4 15 X - M - - 1. 96 =) X-100 =1.96 X = 70-6 15 =) 95 % data of x li0 within ( 910.6, 129 .4 )