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andre [41]
3 years ago
8

The lifetime of lightbulbs that are advertised to last for 4000 hours are normally distributed with a mean of 4250 hours and a s

tandard deviation of 300 hours. What is the probability that a bulb lasts longer than advertised
Mathematics
1 answer:
kobusy [5.1K]3 years ago
6 0

Answer:

79.67% probability that a bulb lasts longer than advertised

Step-by-step explanation:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean \mu and standard deviation \sigma, the zscore of a measure X is given by:

Z = \frac{X - \mu}{\sigma}

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this problem, we have that:

\mu = 4250, \sigma = 300

What is the probability that a bulb lasts longer than advertised?

This is 1 subtracted by the pvalue of Z when X = 4000. So

Z = \frac{X - \mu}{\sigma}

Z = \frac{4000 - 4250}{300}

Z = -0.83

Z = -0.83 has a pvalue of 0.2033

1 - 0.2033 = 0.7967

79.67% probability that a bulb lasts longer than advertised

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- (10)2 + 6(-5)/(-2)

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- 20 + 16

4 ( I think)

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3 years ago
Can someone please help me with this I don’t wanna fail math
aivan3 [116]

Answer: y = mx + b is the slope intercept form of writing the equation of a straight line

Step-by-step explanation:

8 0
2 years ago
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Please help me with this problem, thank you!
motikmotik
It would be 5 im pretty sure...
6 0
2 years ago
A parallelogram has a 70 degree angle and sides 6 cm and 10 cm long. How long are its diagonals?
Verdich [7]
Let the shorter diagonal be x, then
x^2 = 6^2 + 10^2 - 2 x 6 x 10 x cos 70 = 36 + 100 - 120 cos 70 = 136 - 41.04 = 94.96
x = sqrt(94.96) = 9.7 cm

The other angle of the parallelogram is 1/2(360 - 2(70)) = 1/2(360 - 140) = 1/2(220) = 110
Let the longer diagonal be y, then
y^2 = 6^2 + 10^2 - 2 x 6 x 10 x cos 110 = 36 + 100 - 120 cos 110 = 136 + 41.04 = 177.04
y = sqrt(177.04) = 13.3 cm.

Therefore, the length of the diagonals are 9.7 cm and 13.3 cm.
6 0
3 years ago
The cost of belonging to a gym can be modeled by C(m)= 50m + 79.50, where C(m) is the total cost for m months of membership. Sta
erik [133]

Answer:

The slope is 50, which is the cost per month of the gym membership, and 79.50 is the y intercept.  It represents the initial cost to join the gym.

Step-by-step explanation:

C(m)= 50m + 79.50,

This is written in the form y= mx+b where m is the slope and b is the y intercept.

The slope is 50, which is the cost per month of the gym membership, and 79.50 is the y intercept.  It represents the initial cost to join the gym.

3 0
3 years ago
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