$X$ is a normal variable with mean $\mu$ and standard deviation $\sigma$. It is given that&nbs

Question

$X$ is a normal variable with mean $\mu$ and standard deviation $\sigma$. It is given that $P(X > 128) = 0.15$ and that $P(X > 97) = 0.875$. Calculate $\mu$ and $\sigma$.

Accepted Answer

$\mu=113.3074409\ldots$, $\sigma=14.17607658\ldots$ (so $\mu=113.3$, $\sigma=14.2$ to 1 d.p.).

Obtaining unknown mean and variance

Obtaining unknown mean and variance

Solution:

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