Answer: hi hope this helps
Step-by-step explanation:
The lifetime is months is 85.24 months
Step-by-step explanation:
In this question you are supposed to find the months "X' that is exceeded by 10% of the hard drives.
Exceeded by 10% means a value X on the frequency distribution table that is to the right of the mean score of 75 months showing 10% more.This means exceeding 10% will be months above 0.9 (from 100-90=90%=1-0.9=0.1 as a decimal)
In the standard normal distribution table, look for 0.9, closest value is 0.8997 which gives z=1.2 for y-axis and for x-axis 0.08 to give 1.28
So you have z=1.28, mean μ=75 and δ=8, finding X will gives
You apply the formula;
P(z>X-75/8)
P(z>1.28)=0.1
z=X-μ /δ
1.28=(X-75)/8
8*1.28=X-75
10.24=X-75
10.24+75=X
X=85.24 months
Learn More
Percentile in Normal distribution :brainly.com/question/13700221
Keywords: normally distributed, mean, standard deviation, exceeds
#LearnwithBrainly
Answer:
x= 8.4
Step-by-step explanation:
y=0.8
4x + 8y =40
4x + ( 8 x 0.8) = 40
4x + (6.4) =40
4x = 40 - 6.4
4x = 33.6
x = 8.4
<span>In order to find the standard deviation, we first have to calculate the mean (average) of the numbers. To get this we add all the numbers together and then divide by 12 since there are 12 numbers. The mean = 782. Next, we take each number and subtract the mean, taking the result and squaring it. For this we get: 6724, 2209, 10404, 11664, 729, 1764, 12544, 9, 529, 71824, 1444, 1024. Now we sum all of these up and take the average by dividing the sum by 12. Doing this we get 120868/12=10072. The last step is the take the square root of that number to get the standard deviation. The final result is 100.</span>
