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Complete Question
The life of a semiconductor laser at a constant power is normally distributed with a mean of 7,000 hours and a standard deviation of 600 hours. If three lasers are used in a product and they are assumed to fail independently, the probability that all three are still operating after 7,000 hours is closest to? Assuming percentile = 95%
Answer:
0.125
Step-by-step explanation:
Assuming for 95%
z score for 95th percentile = 1.645
We find the Probability using z table.
P(z = 1.645) = P( x ≤ 7000)
= P(x<Z) = 0.95
After 7000 hours = P > 7000
= 1 - P(x < 7000)
= 1 - 0.95
= 0.05
If three lasers are used in a product and they are assumed to fail independently, the probability that all three are still operating after 7,000 hours is calculated as:
(P > 7000)³
(0.05)³ = 0.125
Answer:
$255
Step-by-step explanation:
As, the area of the pool bottom = length x breath
= 20 x 15 = 300 square foot
So for painting
Per square foot = $0.85
So for 300 square foot = $0.85 x 300
= $255
Yes. When solving a problem like this, multiply the base numbers normally, and add the exponents together.
If you need more help, comment below and I'd be happy to assist.
First find the numbers that are divisible by 3.
3, 6, 9, 12, 15, 18, 21, 24
There are 8 numbers divisible by 3 so there are 16 that are not divisible by 3.
P(not div by 3) = 16/24 = 2/3
We can factor out the 4 to get
4(2a^3b^8+ab-4ab^8)
we can also factor out the ab
4ab(2a^2b^7+1-4b^7)
that is factored completely
