Answer:
350 cm2
Step-by-step explanation:
use the formula 2h ( l+b)
Answer:
14.69% probability that defect length is at most 20 mm
Step-by-step explanation:
When the distribution is normal, we use the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this question, we have that:

What is the probability that defect length is at most 20 mm
This is the pvalue of Z when X = 20. So



has a pvalue of 0.1469
14.69% probability that defect length is at most 20 mm
<span>So the question is 25% of what number is 21. Lets turn that into an equation: let x be the number we are looking for. We need to take 25% from it and we know that that is equal to 21. Mathematically: 25% * x= 21. Or: (25/100) * x = 21. When we multiply both sides with 100 and divide both sides by 25 we get: x=21*(100/25). And we get that x=84. </span>