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just olya [345]
3 years ago
14

The mean lifetime of a certain tire is 30,000 miles and the standard deviation is 2500 miles. If we assume nothing about the sha

pe of the distribution, approximately what percentage of all such tires will last between 25,000 and 37,500 miles?
Mathematics
1 answer:
kati45 [8]3 years ago
5 0
A standard deviation is 2500 miles, so the range of 25,000 to 37,500 is 2 standard deviations below, and 3 standard deviation above the mean of 30,000. 
We aren't assuming anything about the distribution, but we sort of have to assume a normal distribution in order to answer. When you don't know anything about a distribution, this is generally what you do.
The general rule for standard deviations is:
+/- 1 SD: +/- 34% of population, for a total of 68%
+/- 2 SD: Another 14% in either direction, for a total of 96% of population.
+/- 3 SD, Another 2% in either direction, which pretty much captures the entire distribution (4 standard deviations from the mean is incredibly rare/unlikely) 
We have a range of +/- 1 SD, so we know that 68% percent o the tire 'population' is captured in the range. We also have one more standard deviation in both directions, so we add 28% to this number to get 96% of the population. We have a third standard deviation above the mean, so we add another 2% to arrive at 98% of the population. 

Answer is 98% of all such tires. 
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Which inequality is shown in this graph
Katena32 [7]

ANSWER

y \leqslant   - 2x - 2

EXPLANATION

The boundary line passes through (-2,2) and (0,-2).

The slope of this line is

m =  \frac{ - 2 - 2}{0 -  - 2}

m =  \frac{ - 4}{2}  =  - 2

The y-intercept is , c=-2.

The slope-intercept form of this line is given by;

y = mx + c

We substitute values to obtain;

y =  - 2x - 2

Since the lower half-plane is shaded the required inequality is

y \leqslant   - 2x - 2

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3 years ago
3*(-4) really confuses need help
Arturiano [62]

Answer:

-12

Step-by-step explanation:

When you multiply a positive by a negative, the answer is always a negative. If you multiply two negatives, the answer is always positive. If you multiply 2 positives, the answer will always be positive.

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3 years ago
Find the product. x3(x2+5x+1)
PtichkaEL [24]

Answer:

Answer = x5+5x4+x3

Step-by-step explanation:

x3(x2+5x+1)

=(x3)(x2+5x+1)

=(x3)(x2)+(x3)(5x)+(x3)(1)

=x5+5x4+x3

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3 years ago
The triangle below are similar. Which similarity statements describe the relationship between the two triangles? Check all that
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Step-by-step explanation:

3 0
3 years ago
483.6 is what percent of 180
liraira [26]

Answer:

We assume, that the number 180 is 100% - because it's the output value of the task.

2. We assume, that x is the value we are looking for.

3. If 100% equals 180, so we can write it down as 100%=180.

4. We know, that x% equals 483.6 of the output value, so we can write it down as x%=483.6.

5. Now we have two simple equations:

1) 100%=180

2) x%=483.6

where left sides of both of them have the same units, and both right sides have the same units, so we can do something like that:

100%/x%=180/483.6

6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 483.6 is what percent of 180

100%/x%=180/483.6

(100/x)*x=(180/483.6)*x       - we multiply both sides of the equation by x

100=0.37220843672457*x       - we divide both sides of the equation by (0.37220843672457) to get x

100/0.37220843672457=x

268.66666666667=x

x=268.66666666667

now we have:

483.6 is 268.66666666667% of 180

4 0
3 years ago
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