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3 years ago

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Find the difference. Simplify completely. Please show work.1. 7/9 - 3/8 2. 5 4/5 - 2 1/4

1 answer:

fenix001 [56]3 years ago

4 0

1. 7/9 - 3/8 = (7·8 - 9·3)/(9·8) = (56 -27)/72 = 29/72

2. (5 4/5) - (2 1/4) = (5 - 2) + (4/5 - 1/4) = 3 + (4·4 -5·1)/(5·4) = 3 11/20

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(a/b) -(c/d) = (ad -bc)/(bd) . . . . a useful formula to remember when working problems like this. It is equivalent to multiplying the first fraction by d/d and the second one by b/b to get a common denominator of bd. Of course if the second fraction is added instead of subtracted, the sign changes in both places.

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In a survey of first graders, their mean height was 51.6 inches with a standard deviation of 3.6 inches. Assuming the heights ar

ki77a [65]

Answer:

Step-by-step explanation:

In a survey of first graders, their mean height was 51.6 inches with a standard deviation of 3.6 inches. Assuming the heights are normally distributed, what height represents the first quartile of these students?

54.03 inches

48.57 inches

48.00 inches

49.17 inches

6 0

1 year ago

sattari [20]

Answer:

(a): <u>x</u><u> </u><u>is</u><u> </u><u>3</u><u> </u><u>and</u><u> </u><u>ky</u><u> </u><u>is</u><u> </u><u>-</u><u>1</u>

<u>(</u><u>b</u><u>)</u><u>:</u><u> </u><u>k</u><u> </u><u>is</u><u> </u><u>-</u><u>2</u>

Step-by-step explanation:

Let: 3x + ky = 8 be <em>e</em><em>q</em><em>u</em><em>a</em><em>t</em><em>i</em><em>o</em><em>n</em><em> </em><em>(</em><em>a</em><em>)</em>

x - 2 ky = 5 be <em>e</em><em>q</em><em>u</em><em>a</em><em>t</em><em>i</em><em>o</em><em>n</em><em> </em><em>(</em><em>b</em><em>)</em>

<em> </em>Then multiply <em>e</em><em>q</em><em>u</em><em>a</em><em>t</em><em>i</em><em>o</em><em>n</em><em> </em><em>(</em><em>a</em><em>)</em><em> </em>by 2:

→ 6x + 2ky = 16, let it be <em>e</em><em>q</em><em>u</em><em>a</em><em>t</em><em>i</em><em>o</em><em>n</em><em> </em><em>(</em><em>c</em><em>)</em>

Then <em>e</em><em>q</em><em>u</em><em>a</em><em>t</em><em>i</em><em>o</em><em>n</em><em> </em><em>(</em><em>c</em><em>)</em><em> </em><em>+</em><em> </em><em>e</em><em>q</em><em>u</em><em>a</em><em>t</em><em>i</em><em>o</em><em>n</em><em> </em><em>(</em><em>b</em><em>)</em><em>:</em>

<em> ${ \sf{(6 + 1)x + (2 - 2)ky = (16 + 5)}} \\ { \sf{7x = 21}} \\ { \sf{x = 3}}$ </em>

<em>T</em><em>h</em><em>e</em><em>n</em><em> </em><em>k</em><em>y</em><em> </em><em>:</em>

${ \sf{2ky = 3 - 5}} \\ { \sf{ky = - 1}}$

${ \bf{y = \frac{1}{2} }} \\ { \sf{ky = - 1}} \\ { \sf{k = - 2}}$

4 0

2 years ago

Find the length of ad in the diagram shown

kvv77 [185]

The answer to this is 7.5.

4 0

2 years ago

Read 2 more answers

The length of a rectangle is twice the width. The area is 162 yd? Find the length and the width.

Tresset [83]

Answer:

length = 2x = 2(9) = 18 yds

Step-by-step explanation:

Let width = x

Let length = 2x

Area = 162 yd2

length × width = Area

2x(x) = 162

2x2 = 162

Divide by 2 on both sides of equation.

x2 = 81

Square-root both sides of equation to undo the exponent.

x = √(81)

x = 9

Substitute this x value into the initial variables.

width = x = 9 yds

length = 2x = 2(9) = 18 yds

6 0

2 years ago

A sample size of n = 64 is drawn from a population whose standard deviation is o = 5.6.

AlekseyPX

Answer:

The margin of error for a 99% confidence interval for the population mean is 1.8025.

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1-0.99}{2} = 0.005$

Now, we have to find z in the Ztable as such z has a pvalue of $1-\alpha$ .

So it is z with a pvalue of $1-0.005 = 0.995$ , so $z = 2.575$

Now, find the margin of error M as such

$M = z*\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

In this problem:

$\sigma = 5.6$

So

$M = 2.575*\frac{5.6}{\sqrt{64}} = 1.8025$

The margin of error for a 99% confidence interval for the population mean is 1.8025.

5 0

2 years ago