Answer
$57.62\%$
Work Step by Step
$\text{z-score}=\frac{\text{data item-mean}}{\text{standard deviation}}$.
Hence $z_1=\frac{109-121}{15}=-0.8, z_2=\frac{133-121}{15}=0.8$.
Then the answer, using the table is: $78.81-21.19=57.62\%$
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