Solution :
Given that ,
P(60 < x < 80) = P[(60 - 70)/ 10) < (x - ) / < (80 - 70) / 10) ]
= P(-1 < z < 1)
= P(z < 1) - P(z < -1)
= 0.8413 - 0.1587
= 0.68
Proportion = 0.68
Question 28 A scientist obtaired a normally distributed population of scores with a mean of 70...
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