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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
Step-by-step explanation:
log <base a> b = x
means
a^x = b
So
3^2 = x^2+7x+21
x^2 + 7x + 21 - 9 = 0
x^2 + 7x + 12 = 0
(x+3)(x+4)
x = -3 or -4
Answer:
8 to 25
Step-by-step explanation:
The total number of lunches sold i
220+120+160 =500
We want the ratio of salads to total lunches
salads: lunches
160: 500
Divide each side by 20
160/20 : 500/20
8:25
Answer:
B
Step-by-step explanation:
its b solve the first equation for y \
hope this helps
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