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Answer:
20 liters of the 40% solution
60-20=40 liters of the 70% solution
Step-by-step explanation:
40%x+70%(60-x)=60%(60)
0.4x+0.7(60-x)=0.6(60)
0.4x+42-0.7x=36
-0.3x+42=36
-0.3x=-42+36
-0.3x=-6
0.3x=6
3x=60
x=60/3
x=20 liters of the 40% solution
60-20=40 liters of the 70% solution
check: 0.4*20=8
0.7*40=28
8+28=36 and 0.6*60=36 also
The mean ( average ) is given as 1200 hours.
The standard deviation is 200, sample size is 100.
Find the standard error:
√(200^2 / 100) = 20
Now calculate the confidence interval. For 95% the Z number is 1.96
Multiply Z by the standard error:
1.96 x 20 =39.2
Now find the range that the mean should be within:
1200 - 39.2 = 1160.8
1200 + 39.2 = 1239.2
The samples should be between 1160.8 and 1239.2 for a 95% confidence interval.
Since the average was 1050, which is below 1160.8 the bulbs are not in compliance.
