79 x 31 rounding or compatible numbers . show how you estimate

Mathematics

1 answer:

Lubov Fominskaja [6]3 years ago

8 0

Answer:

80 × 30 = 2,400

Step-by-step explanation:

We can easily round 79 up to 80 and round 31 down to 30. This would make our expression 80 × 30, which is much easier to compute. We just take 8 × 3 (which is 24) and add two zeros onto the end of the number. This yields us an answer of 2,400 which is very close to the actual multiplication of 79 × 31 which is 2,449 (only 49 more than our estimation).

You might be interested in

Which is a solution to the equation 6x + y = –4?

KatRina [158]

1. Make y the subject of the equation
y = -4 - 6x

2. Substitute values for guess and check
8 = -4 - (6 x 2)
8 = -4 - 12
This is incorrect.

2 = -4 - (6 x 1)
2 = -4 -6
This is incorrect.

-10 = -4 - (6 x 1)
-10 = -4 -6
This is correct.

The correct answer is C.

7 0

3 years ago

"a pollster wishes to estimate the number of left-handed scientists. how large of a sample is needed in order to be 98% confiden

nadezda [96]

The sample size should be 250.

Our margin of error is 4%, or 0.04. We use the formula

$\text{ME}=z\sqrt{\frac{\hat{p}(1-\hat{p})}{n}}$

To find the z-score:
Convert 98% to a decimal: 0.98
Subtract from 1: 1-0.98 = 0.02
Divide both sides by 2: 0.02/2 = 0.01
Subtract from 1: 1-0.01 = 0.99

Using a z-table (http://www.z-table.com) we see that this value has a z-score of approximately 2.33. Using this, our margin of error and our proportion, we have:

$0.04=2.33\sqrt{\frac{0.08(1-0.08)}{n}}
\\
\\0.04=2.33\sqrt{\frac{0.08(0.92)}{n}}$

Divide both sides by 2.33:
$\frac{0.04}{2.33}=\sqrt{\frac{0.08(0.92)}{n}}$

Square both sides:
$(\frac{0.04}{2.33})^2=\frac{0.08(0.92)}{n}$

Multiply both sides by n:
$(\frac{0.04}{2.33})^2n=0.08(0.92)$

Divide both sides to isolate n:
$\frac{0.08(0.92)}{(\frac{0.04}{2.33})^2}=n
\\
\\249.73=n
\\n\approx 250$

4 0

3 years ago

In 1910, halley's comet traveled close to earth about 1/7 of the distance from the earth to the sun. Earth's distance from the s

otez555 [7]

Answer:

Imma answer this because I don’t want this to get deleted for not bein answered and there free point who wouldn’t want them, lol :)

Step-by-step explanation:

6 0

3 years ago

Which of the following points lies on the graph of the function y= 2.3*?

Rainbow [258]

If the equation is $y = 2\cdot 3^x$ (2 times 3^x)