# random variable x is normally distributed with mean mu87 and standard deviation sigma5. Find the indicated probability?

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- Wayne DeguManLv 73 months agoFavourite answer
P(x < 80) => P(z < (80 - 87)/5)

i.e. P(z < -1.4)

By symmetry this is P(z > 1.4)

Hence, 1 - P(z < 1.4)

From normal tables we get:

1 - 0.91924 => 0.08076

so, 0.0808...to 4 d.p.

i.e. about 8.1%

:)>

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