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3 years ago

What is the square root of 81

Mathematics

2 answers:

Kay [80]3 years ago

7 0

The square root of 81 is 9
Your answer is 9
Work:
9 x 9 = 81

valina [46]3 years ago

4 0

The square root of 81 is 9.

9 x 9 = 81
81 ÷ 9 = 9

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A travel trailer is bought at the price of $35,000. The value decreases at the rate of .25 every year (t). The exponential expre

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3 years ago

Given that ∠ABD = 71°, which equation could be used to solve problems involving the relationships between ∠DBC and ∠ABC?

dexar [7]

Step-by-step explanation:

one could be that all the angles add up to 180

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3 years ago

Divide 5600 in the ratio 4 :5:7

Elis [28]

Answer:

Step-by-step explanation:

So in our case, let assume 'x' as a common factor.

Thus,

4x + 5x + 7x = 5600;

16x = 5600;

x = 5600/16 = 350.

So,

4x= 350*4 =1400;

5x= 350*5 = 1750; &

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Your answer is, 5600 = 1400+1750+2450 which is in ratio of 4:5:7.

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2 years ago

If f(x) = 1 - 2x^3, find the inverse of f.

Artyom0805 [142]

Swap x and y's positions

f(x) is another way of saying y, so basically tha initial function is y = 1-2x^3.

Change it up to x = 1-2y^3 and solve for y

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(X - 1)/-2 = y^3

So the cube root of ((x-1)/2) = y

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3 years ago

Let the abbreviation PSLT stand for the percent of the gross family income that goes into paying state and local taxes. Suppose

gavmur [86]

Answer:

Number of families that should be surveyed if one wants to be 90% sure of being able to estimate the true mean PSLT within 0.5 is at least 43.

Step-by-step explanation:

We are given that one wants to estimate the mean PSLT for the population of all families in New York City with gross incomes in the range $35.000 to $40.000.

If sigma equals 2.0, we have to find that how many families should be surveyed if one wants to be 90% sure of being able to estimate the true mean PSLT within 0.5.

Here, we will use the concept of Margin of error as the statement "true mean PSLT within 0.5" represents the margin of error we want.

SO, Margin of error formula is given by;

Margin of error = $Z_(_\frac{\alpha}{2}_ ) \times \frac{\sigma}{\sqrt{n} }$

where, $\alpha$ = significance level = 10%

$\sigma$ = standard deviation = 2.0

n = number of families

Now, in the z table the critical value of x at 5% ( $\frac{0.10}{2} = 0.05$ ) level of significance is 1.645.

SO, Margin of error = $Z_(_\frac{\alpha}{2}_ ) \times \frac{\sigma}{\sqrt{n} }$

0.5 = $1.645 \times \frac{2}{\sqrt{n} }$

$\sqrt{n} =\frac{2\times 1.645 }{0.5}$

$\sqrt{n} =6.58$

n = $6.58^{2}$

= 43.3 ≈ 43

Therefore, number of families that should be surveyed if one wants to be 90% sure of being able to estimate the true mean PSLT within 0.5 is at least 43.

4 0

3 years ago