A multiplication is zero if and only if at least one of the factors is zero. So, in this case, the multipications equals zero when
The first equation has no real solutions, because is a square, and thus it's positive. If you add 4 to a positive number, the result can't be zero.
The second equation has the solution
So, globally, the expression equals zero if and only if
Answer:
340
Step-by-step explanation:
The first step is finding the percentage of those who fail within 19 months.
Problems of normally distributed samples can be solved using 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 problem, we have that:
The proportion is the pvalue of Z when X = 19. So
has a pvalue of 0.6808.
Jolt is expected to replace 0.6808 of the connectors sold. Out of 500, that is, on average, 0.6808*500 = 340.
Jolt expects to replace, on average, 340 of the connectors sold.