Ask question

Ask question

All categories

3 years ago

5

Sixteen college freshmen were asked to record the number of alcoholic drinks they typically consume in a week. Here are their da

ta: 2, 4, 6, 0, 1, 10, 9, 0, 6, 3, 6, 8, 5, 4, 6, 2. What is the variance of the number of alcoholic drinks consumed per week?
a.3.26
b.2.96
c.12.25
d.8.75

1 answer:

rjkz [21]3 years ago

7 0

Solution: The correct option is d. 8.75

<u>Explanation:</u>

The formula for variance is:

$Variance =\frac{\sum(x-\bar{x})^{2}}{n}$

First we need to find the mean $\bar{x}$ of the given data:

$\bar{x}=\frac{2+4+6+0+1+10+9+0+6+3+6+8+5+4+6+2}{16}=\frac{72}{16} =4.5$

Now let's find $\sum(x-\bar{x})^{2}$ , please have a look at the attached picture:

$\therefore Variance = \frac{140}{16}=8.75$

You might be interested in

Write the quotient with the decimal point placed correctly 80 ÷ 50 = 16

Katyanochek1 [597]

Answer:

1.6

Step-by-step explanation:

8 0

2 years ago

Read 2 more answers

find the centre and radius of the following Cycles 9 x square + 9 y square +27 x + 12 y + 19 equals 0

Citrus2011 [14]

Answer:

Radius: $r =\frac{\sqrt {21}}{6}$

$Center = (-\frac{3}{2}, -\frac{2}{3})$

Step-by-step explanation:

Given

$9x^2 + 9y^2 + 27x + 12y + 19 = 0$

Solving (a): The radius of the circle

First, we express the equation as:

$(x - h)^2 + (y - k)^2 = r^2$

Where

$r = radius$

$(h,k) =center$

So, we have:

$9x^2 + 9y^2 + 27x + 12y + 19 = 0$

Divide through by 9

$x^2 + y^2 + 3x + \frac{12}{9}y + \frac{19}{9} = 0$

Rewrite as:

$x^2 + 3x + y^2+ \frac{12}{9}y =- \frac{19}{9}$

Group the expression into 2

$[x^2 + 3x] + [y^2+ \frac{12}{9}y] =- \frac{19}{9}$

$[x^2 + 3x] + [y^2+ \frac{4}{3}y] =- \frac{19}{9}$

Next, we complete the square on each group.

For $[x^2 + 3x]$

1: Divide the $coefficient\ of\ x\ by\ 2$

2: Take the $square\ of\ the\ division$

3: Add this $square\ to\ both\ sides\ of\ the\ equation.$

So, we have:

$[x^2 + 3x] + [y^2+ \frac{4}{3}y] =- \frac{19}{9}$

$[x^2 + 3x + (\frac{3}{2})^2] + [y^2+ \frac{4}{3}y] =- \frac{19}{9}+ (\frac{3}{2})^2$

Factorize

$[x + \frac{3}{2}]^2+ [y^2+ \frac{4}{3}y] =- \frac{19}{9}+ (\frac{3}{2})^2$

Apply the same to y

$[x + \frac{3}{2}]^2+ [y^2+ \frac{4}{3}y +(\frac{4}{6})^2 ] =- \frac{19}{9}+ (\frac{3}{2})^2 +(\frac{4}{6})^2$

$[x + \frac{3}{2}]^2+ [y +\frac{4}{6}]^2 =- \frac{19}{9}+ (\frac{3}{2})^2 +(\frac{4}{6})^2$

$[x + \frac{3}{2}]^2+ [y +\frac{4}{6}]^2 =- \frac{19}{9}+ \frac{9}{4} +\frac{16}{36}$

Add the fractions

$[x + \frac{3}{2}]^2+ [y +\frac{4}{6}]^2 =\frac{-19 * 4 + 9 * 9 + 16 * 1}{36}$

$[x + \frac{3}{2}]^2+ [y +\frac{4}{6}]^2 =\frac{21}{36}$

$[x + \frac{3}{2}]^2+ [y +\frac{4}{6}]^2 =\frac{7}{12}$

$[x + \frac{3}{2}]^2+ [y +\frac{2}{3}]^2 =\frac{7}{12}$

Recall that:

$(x - h)^2 + (y - k)^2 = r^2$

By comparison:

$r^2 =\frac{7}{12}$

Take square roots of both sides

$r =\sqrt{\frac{7}{12}}$

Split

$r =\frac{\sqrt 7}{\sqrt 12}$

Rationalize

$r =\frac{\sqrt 7*\sqrt 12}{\sqrt 12*\sqrt 12}$

$r =\frac{\sqrt {84}}{12}$

$r =\frac{\sqrt {4*21}}{12}$

$r =\frac{2\sqrt {21}}{12}$

$r =\frac{\sqrt {21}}{6}$

Solving (b): The center

Recall that:

$(x - h)^2 + (y - k)^2 = r^2$

Where

$r = radius$

$(h,k) =center$

From:

$[x + \frac{3}{2}]^2+ [y +\frac{2}{3}]^2 =\frac{7}{12}$

$-h = \frac{3}{2}$ and $-k = \frac{2}{3}$

Solve for h and k

$h = -\frac{3}{2}$ and $k = -\frac{2}{3}$

Hence, the center is:

$Center = (-\frac{3}{2}, -\frac{2}{3})$

6 0

2 years ago

Show that if u+v and u-v are orthognal, then the vectors u and v must have the same length.

pashok25 [27]

Answer with Step-by-step explanation:

We are given that

u+ v and u-v are orthogonal

We have to prove that u and v must have the same length.

When two vector a and b are orthogonal then

$a\cdot b=0$

By using the property

$(u+v)\cdot (u-v)=0$

We know that

$(a+b)\cdot (a-b)=\mid a\mid^2-\mid b\mid^2$

$\mid u\mid ^2-\mid v\mid^2=0$

$\mid u\mid^2=\mid v\mid^2$

Magnitude is always positive

When power of base on both sides are equal then base will be equal

Therefore,

$\mid u\mid=\mid v\mid$

Hence, the length of vectors u and v must have the same length.

5 0

3 years ago

How can you use multiplication in your everyday life?

Bas_tet [7]

Answer:

On kitchen. Yes. there also we use multiplication. If we are trying to cook something from the recipe website, they tell to add 1 glass of water for 100 gm of rice. But we measure the amount of water based on the quantity of the rice. It’s simple multiplication.

Travelling with your friends. If we are travelling with our friends in a public transport facility like bus or metro, we need to buy multiple tickets. There we need to do multiplication.

Step-by-step explanation:

5 0

2 years ago

Solve the problem:

Over [174]

Answer:

Step-by-step explanation:

ohfpifpijpijsfpjspijpsijfpsjfpsjfpisjfpijsfpsijf

4 0

2 years ago