Stanford-Binet IQ Test scores are normally distributed with a mean score of 100

Question

Stanford-Binet IQ Test scores are normally distributed with a mean score of 100 and a standard deviation of 16. Find the probability that a randomly selected person has an IQ test score

Problem 1 Stanford-Binet IQ Test scores are normally distributed with a mean score of 100 and a standard deviation of 16. Find the probability that a randomly selected person has an IQ test score a) Over 140. Answer Canvas Quiz 5-1 and 5-2. (2 points) b) Under 88. Answer Canvas Quiz 5-3 and 5-4. (2 points) c) Between 72 and 128. Answer Canvas Quiz 5-5 to 5-7. (3 points) d) Between +/- 1.5 standard deviations of the mean. Answer Canvas Quiz 5-8. (1 point)

Explanation / Answer

solution:

(a) P(x > 140)

= P(z > 2.5)

= 1 – .9938

= .0062

(b) P(x < 88)

= P(z < –.75)

= .2266

(c) P(72 < x < 128)

=P(–1.75 < z < 1.75)

= .9599 – .0401

= .9198

(d) P(–1.5 £ z £ 1.5)

= .9332 – .0668

= .8664

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