All categories

2 years ago

Can someone help me !!

Mathematics

1 answer:

svetoff [14.1K]2 years ago

3 0

Answer:

x = 15

Step-by-step explanation:

Create the proportion: 5/7 = x/21

Multiply both sides by 21: 15 = x

You might be interested in

What is the value of 3 in 803,040

mel-nik [20]

The value of 3 is a thousand.

4 0

2 years ago

Read 2 more answers

Calculate the sample mean and sample variance for the following frequency distribution of heart rates for a sample of American a

spin [16.1K]

Answer:

$Mean = 68.9$

$s^2 =18.1$ --- Variance

Step-by-step explanation:

Given

$\begin{array}{cccccc}{Class} & {51-58} & {59-66} & {67-74} & {75-82} & {83-90} \ \\ {Frequency} & {6} & {3} & {11} & {13} & {4} \ \end{array}$

Solving (a): Calculate the mean.

The given data is a grouped data. So, first we calculate the class midpoint (x)

For 51 - 58.

$x = \frac{1}{2}(51+58) = \frac{1}{2}(109) = 54.5$

For 59 - 66

$x = \frac{1}{2}(59+66) = \frac{1}{2}(125) = 62.5$

For 67 - 74

$x = \frac{1}{2}(67+74) = \frac{1}{2}(141) = 70.5$

For 75 - 82

$x = \frac{1}{2}(75+82) = \frac{1}{2}(157) = 78.5$

For 83 - 90

$x = \frac{1}{2}(83+90) = \frac{1}{2}(173) = 86.5$

So, the table becomes:

$\begin{array}{cccccc}{x} & {54.5} & {62.5} & {70.5} & {78.5} & {86.5} \ \\ {Frequency} & {6} & {3} & {11} & {13} & {4} \ \end{array}$

The mean is then calculated as:

$Mean = \frac{\sum fx}{\sum f}$

$Mean = \frac{54.5*4+62.5*3+70.5*11+78.5*13+86.5*4}{6+3+11+13+4}$

$Mean = \frac{2547.5}{37}$

$Mean = 68.9$ -- approximated

Solving (b): The sample variance:

This is calculated as:

$s^2 =\frac{\sum (x - \overline x)^2}{\sum f - 1}$

So, we have:

$s^2 =\frac{(54.5-68.9)^2+(62.5-68.9)^2+(70.5-68.9)^2+(78.5-68.9)^2+(86.5-68.9)^2}{37 - 1}$

$s^2 =\frac{652.8}{36}$

$s^2 =18.1$ -- approximated

5 0

2 years ago

brad wants to open a new saving account. he finds one that returns 3% on his investment each year.Use the varibles to write a fo

Vsevolod [243]

3% is the interest so you would do 3% of the investment plus the original investment so 3%×I=z and then z+I=the answer. sorry if this didnt help I'm new and I tried my best sorry!

3 0

2 years ago

A student wishes to compare the cost of textbooks from two sellers. The same forty textbooks are priced at both seller A and sel

MrRissso [65]

Would it like.. not be C?? Im guessing its C (:

6 0

3 years ago

4y= -6x +8 <br>find the y-intercept

ivanzaharov [21]

First, divide each side by 4 to get y alone on the left side.

y=-6/4x+2

The y intercept is 2

7 0

3 years ago