Answer:
A) Between 388 and 450
B) Between 357 and 481
C) Between 326 and 512
D) 99.995%
E) 72.907%
Step-by-step explanation:
We are given;
Mean; x¯ = 419 minutes
Standard deviation; σ = 31 minutes
A) From the empirical rule, 68% falls within 1 standard deviation.
Thus, it will be between;
419 - 1(31) and 419 + 1(31)
Thus gives;
Between 388 and 450
B) From the empirical rule, 95% falls within 2 standard deviation.
Thus, it will be between;
419 - 2(31) and 419 + 2(31)
Thus gives;
Between 357 and 481
C) From the empirical rule, 99.7% falls within 2 standard deviations.
Thus, it will be between;
419 - 3(31) and 419 + 3(31)
Thus;
Between 326 and 512
D)between 359 and 479 minutes, we will use z-s roe formula;
z = (479 - 359)/31
z = 3.871
From the z-table attached, we see that the probability is 0.99995 and as such, the percentage is 99.995%
E) worker spent 400 minutes on the job.
Thus;
z = (419 - 400)/31
z = 0.613
From z-tables, p = 0.72907
In percentage, we have; 72.907%
