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leva [86]
3 years ago
9

A GE lightbulb is supposed to last for 1,200 hours. In fact, light bulbs of this type last only 1,185 hours with a standard devi

ation of 70 hours. What is the probability that a sample of 100 lightbulbs will have an average life of at least 1,200 hours? Mathematics
Mathematics
1 answer:
dybincka [34]3 years ago
7 0
This can be solved using the formula for t test which is = x - mu over standard deviation divided by the square root of the number of samples. In this case, it is 1185 - 1200 over 70 divided by square root of 100 which give us a value of 2.14 which is equal to .9839 in area. Only rarely, just over one time in a hundred tries of 100 light bulbs, would the average life exceed 1200 hours.
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A hot air balloon is flying at a constant speed of 20 mi/h at a bearing of N 36° E. There is a 10mi/h cross wind blowing due eas
Ksju [112]

Answer:

The actual speed = 27.12 mi/h

Direction = 36.5° in NE(north of east)

Step-by-step explanation:

As given , A hot air balloon is flying at a constant speed of 20 mi/h at a bearing of N 36° E.

⇒θ = 36°

Let v₀ be the constant speed, then v₀ = 20

Let vₓ be the speed in East direction

     v_{y} be the speed in North direction

So,

vₓ  = v₀ sin(θ) = 20 sin(36°) + 10 ( As given, There is a 10mi/h cross wind blowing due east.)

⇒vₓ  = 20(0.588) + 10 = 11.76 + 10 = 21.76 mi/h

and   v_{y}  = v₀ cos(θ) = 20 cos(36°) = 20(0.809) = 16.18 mi/h

Now,

the actual speed = √(vₓ)² + (v_{y})²

                            = √(21.76)² + (16.18)²

                            = √473.498 + 261.792

                            = √735.29 =  27.12

⇒The actual speed = 27.12 mi/h

Now,

Direction = θ = tan^{-1}(\frac{v_{y} }{v_{x} } ) = tan^{-1}(\frac{16.18 }{21.76 } ) =  tan^{-1}(0.74) = 36.5

⇒ Direction = 36.5° in NE(north of east)

7 0
2 years ago
Find the answer please
xz_007 [3.2K]

1st set = 4 letters

2nd set = 4x 4 = 16 letters

3rd set = 16 x 4 = 64 letters

4th set = 64 x 4 = 256 letters

5th set = 256 x 4 = 1,024 letters

6th set =1024 x 4 = 4,096 letters

7th set = 4096 x 4 = 16,384 letters

8th set = 16,384 x 4 = 65,536 letters

Each letter cost 2

Total cost = 65,536 x 2 = 131,072

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Answer:

Like yeah right

Step-by-step explanation:

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7nadin3 [17]
The slope of the line is 3/4
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During the soccer season, Sheka scored 4 goals. Dylan scored 8 times as many goals as Sheka.
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Answer:

it's B

Step-by-step explanation:

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2 years ago
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