Answer:
A.
Step-by-step explanation:
<span>We know that the runner completed her first race in 17.8 seconds and that she completed her second race in 16.9 seconds. Then the difference between the first race and the second race is .9 seconds. Now we divide .9 by 17.8 and multiply by 100 to get the percent decrease. We get 5.06%. The percent decrease in her time is 5%.</span>
Answer:
1440
Step-by-step explanation:
It’s 1440
Answer:
Step-by-step explanation:
Complete question :
The lifetimes of a certain type of calculator battery are normally distributed. The mean lifetime is 400 days, with a standard deviation of 50 days. For a sample of 6000 new batteries, determine how many batteries will last: 360 and 460 days
Answer:
0.67307
Step-by-step explanation:
Given that :
Mean, m = 400
Standard deviation, s = 50
Sample size, n = 6000
Obtain the standardized score :
Zscore =(x - m) / s
For X = 360
P(x < 360)
Zscore =(360 - 400) / 50
Zscore = - 40 / 50
Zscore = - 0.8
P(Z < - 0.8) = 0.21186
For X = 460
P(x < 460)
Zscore =(460 - 400) / 50
Zscore = 60 / 50
Zscore = 1.2
P(Z < 1.2) = 0.88493
P(Z < 1.2) - P(Z < - 0.8)
0.88493 - 0.21186
= 0.67307
