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3 years ago

URGENT! CINE SE PRICEPE LA MATEMATICĂ. [CLASA A 8-A]

Mathematics

1 answer:

kiruha [24]3 years ago

7 0

The answer is yes but its could be false or 6:00

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Calculate the sample standard deviation and sample variance for the following frequency distribution of heart rates for a sample

adelina 88 [10]

Answer:

$\sigma = 12.5$ ---- sample standard deviation

$\sigma^2 = 157.2$ ---- sample variance

Step-by-step explanation:

Solving (a): The sample variance

First, we calculate the midpoint of each class (this is the average of the limits)

So, we have:

$x_1 = \frac{56 + 64}{2} = 60$

$x_2 = \frac{65 + 73}{2} = 69$

And so on

So, the table becomes:

$\begin{array}{cc}{x} & {f} & {60} & {11} & {69} & {15} & {78} & {14} & {87} & {4} & {96} & 11 \ \end{array}$

Calculate the mean

$\bar x = \frac{\sum fx}{\sum f}$

$\bar x = \frac{60*11+69*15+78*14+87*4+96*11}{11+15+14+4+11}$

$\bar x = \frac{4191}{55}$

$\bar x = 76.2$

The variance is:

$\sigma^2 = \frac{\sum f(x - \bar x)^2}{\sum f - 1}$

So, we have:

$\sigma^2 = \frac{(60 - 76.2)^2*11+(69 - 76.2)^2*15+(78 - 76.2)^2 *14+(87 - 76.2)^2*4+(96 - 76.2)^2*11}{11+15+14+4+11-1}$

$\sigma^2 = \frac{8488.8}{54}$

$\sigma^2 = 157.2$

The sample standard deviation is:

$\sigma = \sqrt{\sigma^2$

$\sigma = \sqrt{157.2$

$\sigma = 12.5$

Solving (b): The sample variance

In (a), we calculate the sample variance to be:

$\sigma^2 = 157.2$

6 0

2 years ago

What is the quotient? 1060 ÷ 48 Enter your answer as a mixed number in the simplest form in the box.

Maslowich

265/12 is the quotient as a mixed number in simplest form of 1060÷48.

7 0

2 years ago

Read 2 more answers

A circle has diameter 18 inches, and a chord is 14 inches long. What is the distance in inches from the chord to the center of t

Mazyrski [523]

Answer:

Let O be the center of a circle whose radius is r cm , in which AB= 14 cm long

cord is at a distanceof 24 cm from O. Draw a perpendicular OD on AB , thus ,

OD= 24 cm.

In right angled triangle. ODB

OB^2 = OD^2+ DB^2

r^2 =(24)^2+(AB/2)^2 = 576+(14/2)^2

r^2 = 576+ 49=625

r = √625. =25 cm. Answer.

7 0

2 years ago

Math is hard, 7th grade math too..

VARVARA [1.3K]

Answer:

i could be wrong but i think its x=3 :(

Step-by-step explanation:

3 0

2 years ago

there are 7 boys and girls in a club. How many different ways to form a queue starting with a girl after each girl?

Soloha48 [4]

Answer:

7 girls can go in the first place, 6 in the second, etc.

7! ways is the number of ways to arrange the girls.

likewise the boys can be arranged in 7! ways

The total number of ways becomes 7! * 7!

7! * 7! = 25,401 600 ways

8 0

2 years ago