very positive about these results
I don’t know what the heck is
The number of failures in 3000 hours with an MTBF of 6 hours is 500. When the MTBF is 8 hours, the number of failures drops to 375, a savings of the cost of 125 failures, or $25,000.
Salaries are normally distributed
Average salary per hour: $6.50 ⇒ μ=$6.50
σ=$0.45 (Standard deviation)
Probability that the selected worker will earn $6.75:
P(x>6.75)
Now you must standardize the normal random variables:
If x~N (μσ²) => Z=(x-μ)/σ
Z=(6.75-6.50)/0.45
Z=0.556 => P(Z>0.556)= ? (To find this probability, you must use the tables for Standard normal distribution).
Then:
P(Z>0.556)=0.2877
The probability of selecting a worker who earns more than $ 6.75 is 28.7%
