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3 years ago

A+b=77,a-b=13 care sun nr

1 answer:

3 0

It's a simultaneous equation:
Steps:
1.Number the equations..

a+b=77 -1
a-b=13 -2

2. Choose what variable you want to use. In this case I would use the "b". Since the signs in front of the "b's" are different, add the two equations together

a + b = 77
+ + +
a (-b) = 13

Which gives;
2a = 90

Then solve to find a:
2a=90
a= 90/2
a=45

3.Then plug the "a" value into any of the original equations to find the "b" value. I would use equation 1 since the all the variables are positive.

a + b = 77
(45) + b = 77
b=77-45
b=32

4.Solution

a=45
b=32

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3 years ago

Round 564,938 to the nearest 1000 is it 565000

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Answer:

YES!

Step-by-step explanation:

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3 years ago

A sprinkler rotates 360 degrees the total are watered is 204yds squared<br> what is the raduius

SIZIF [17.4K]

The radius of the area the sprinkler has watered is 8.06 yards.

<h3>What is Rotation ?</h3>

Rotation is spinning around a fixed point with a fixed radius in circular motions.

It is given that a sprinkler rotates 360 degree

The area watered is 204 sq. yards

Radius = ?

A sprinkler rotates in circle

Therefore the area of the circle = π r²

204 = π r²

204 * 7 /22 = r²

r² = 64.91

r = 8.06 yards

Therefore the radius of the area the sprinkler has watered is 8.06 yards.

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2 years ago

g Annual starting salaries in a certain region of the U. S. for college graduates with an engineering major are normally distrib

algol13

Answer:

The probability that the sample mean would be at least $39000 is of 0.8665 = 86.65%.

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score 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 p-value, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$ .