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the age when a child gets their first cell phone is n(17, 42) . what is the probability a randomly chosen kid doesn't get his first cell phone until after he is 12?

1 Answer

3 votes

Answer:

0.992

Explanation:

Given:

μ = 17

τ² = 4.2 (it should not be 42)


\tau=√(4.2)

x = 12


Z=(x-\mu)/(\tau)


=(12-17)/(√(4.2) )


=-2.430

P(Z > -2.430) = 0.992

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