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exis [7]
3 years ago
7

The mean life of a certain brand of auto batteries is 44 months with a standard deviation of 3 months. Assume that the lives of

all auto batteries of this brand have a bell-shaped distribution. Using the empirical rule, find the percentage of auto batteries of this brand that have a life of 35 to 53 months. Round your answer to one decimal place.
Mathematics
1 answer:
alisha [4.7K]3 years ago
6 0

Answer:

99.7%

Step-by-step explanation:

Using the z score formula

z-score is z = (x-μ)/σ

where:

x = raw score

μ = population mean

σ = population standard deviation.

a) for x = raw score = 35

μ = population mean = 44

σ = population standard deviation =3

z = (35 - 44)/3

z = -9/3

z = -3

b) for x = raw score = 53

μ = population mean = 44

σ = population standard deviation =3

z = (53 - 44)/3

z = 9/3

z = 3

We would use the standard normal distribution table to find their probabilities

P(Z<=-3)=0.0013499

P(Z<=+3)=0.99865

So P(-3<=Z<=3)=0.99865 - 0.0013499 = 0.9973

Converting to percentage = 0.9973 × 100 = 99.73%

Therefore, the percentage of auto batteries of this brand that have a life of 35 to 53 months to one decimal place is 99.7%

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For every nickel increase in price, the subscriptions to the Perrysville Paper decreases by 5 people. If 1,256 people currently
SpyIntel [72]

Answer:

1,231 people

Step-by-step explanation:

1,256 people currently subscribe. $0.25 is 5 nickels, and for every nickel the price is raised, 5 people unsubscribe. That's 1 person per cent. 25 people will unsubscribe for every $0.25 the price is raised. 1,256-25 is 1,231, so 1,231 people will continue to subscribe after the price increase.

3 0
3 years ago
6 feet<br> 12 feet<br> What is the area of the given composite shape?
Reika [66]

Answer:

choice A; 128.52 square feet

Step-by-step explanation:

This shape is made up of a semi-circle and a rectangle. The area of the rectangle will be 12*6 = 72 sq ft.

The formula for area of a circle is \pi*r^{2}. also r=radius. We are given the diameter, 12 feet. The radius is diameter/2, so the radius of the circle will be 6 feet.

Since pi is infinite we round it to 3.14.

Plug in the values and our expression will be (3.14*6^{2})/2 because it is a semi-circle. Simplify that to (3.14*36)/2 = 113.04/2 = 56.52 sq ft.

Remember to add the area of the rectangle and semi-circle. 72 + 56.52 = 128.52 sq ft.

3 0
2 years ago
You are one of 18 people entering a contest. What is the probability that your name will be drawn first?
telo118 [61]

Answer:

1/18 or 55.5%

Step-by-step explanation:

hope u enjoy!!! add me in the brainly list

4 0
3 years ago
115% of what number is 120
malfutka [58]
115% is the same as 1.15
some number = x

115% of some number is 120
1.15 of x is 120
1.15 * x = 120

x = 104.3478
<span>x ≈ 104.3</span>
7 0
3 years ago
The sum of two numbers is 52. The smaller number is 18 less than the larger number. What are the numbers?
ch4aika [34]

x + y = 52

x = y - 18

Adding,

2x + y = 52 + y - 18

2x = 34

x = 17

y = x + 18 = 35

Check: x+y = 17+35 = 52, good

Answer: 17 and 35

7 0
3 years ago
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