To answer this item, we are first to calculate the values of the length of this particular metal rod that is 0.045 cm less than the given,
Lower limit = 20.5 cm - 0.045 cm = 20.455 cm
Also, we calculate for the upper limit by adding 0.045 cm to the given length.
Upper limit = 20.5 cm + 0.045 cm = 20.545 cm
Thus, the answer to this item is D.
You need to know the distribution's mean and standard deviation.

Transforming to the standard normal distribution, and letting

denote the standard deviation,

The z-score corresponding to this probability is approximately

, so you have
Answers: [E] and [F] .
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[E]: 8²ˣ ;
Note: (8²)ˣ = 8²ˣ ; (8²)ˣ = (64)ˣ ;
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The answer for this is 4.