Question

The heights of 10 year old children has a normal probability distribution with mean of 54.6 inches and standard deviation of 5.7 inches. What is the approximate probability that a randomly selected 10-year old child will be more than 51.75 inches tall? Group of answer choices 0.69 0.31 0.62 0.67 0.93

Answer 1

Answer:

a) 0.69

The probability that a randomly selected 10-year old child will be more than 51.75 inches tall

P(X>51.75 ) = 0.6915

Step-by-step explanation:

Step(i):-

Given mean of the Population = 54.6 inches

Given standard deviation of the Population = 5.7 inches

Let 'X' be the random variable of normal distribution

Let 'X' = 51.75 inches

$Z = \frac{x-mean}{S.D} = \frac{51.75-54.6}{5.7} = -0.5$

Step(ii):-

The probability that a randomly selected 10-year old child will be more than 51.75 inches tall

P(X>51.75 ) = P(Z>-0.5)

                  = 1 - P( Z < -0.5)

                 =   1 - (0.5 - A(-0.5))

                =    1 -0.5 + A(-0.5)

               =    0.5 + A(0.5)    (∵A(-0.5)= A(0.5)

              =     0.5 +0.1915

              =  0.6915

Conclusion:-

The probability that a randomly selected 10-year old child will be more than 51.75 inches tall

P(X>51.75 ) = 0.6915