Extruded plastic rods arc automatically cut into nominal len

Extruded plastic rods arc automatically cut into nominal lengths of 7 inches. Actual lengths arc normally distributed about a mean of 7 inches and their standard deviation is 0.07 inch. What proportion of the rods has lengths that are outside the tolerance limits of 6.86 and 7.14 inches? To what value docs the standard deviation need to be changed if 98% of the rods must be within tolerance?

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