Please help !!!!!!!!!!!

Two college roommates have each committed to donating to charity each week for the next year. The roommates’ weekly incomes are

schepotkina [342]

Answer:

C. 5 weeks.

Step-by-step explanation:

In this question we have a random variable that is equal to the sum of two normal-distributed random variables.

If we have two random variables X and Y, both normally distributed, the sum will have this properties:

$S=X+Y\\\\\ \mu_S=\mu_X+\mu_Y=30+60=90\\\\\sigma_S=\sqrt{\sigma_X^2+\sigma_Y^2}=\sqrt{10^2+20^2}=\sqrt{100+400}=\sqrt{500}=22.36$

To calculate the expected weeks that the donation exceeds $120, first we can calculate the probability of S>120:

$z=\frac{S-\mu_S}{\sigma_S} =\frac{120-90}{22.36}=\frac{30}{22.36}=1.34\\\\P(S>120)=P(z>1.34)=0.09012$

The expected weeks can be calculated as the product of the number of weeks in the year (52) and this probability:

$E=\#weeks*P(S>120)=52*0.09012=4.68$

The nearest answer is C. 5 weeks.

6 0

2 years ago

I need this answer fast! Please!

vovangra [49]

Answer:

$\large\boxed{\begin{array}{c|c|c|c}Length:&4cm&2cm&8cm\\Width:&6cm&12cm&3cm\\Height:&9cm&9cm&9cm\end{array}}$

Step-by-step explanation:

The formula of a volume of a cube with side length a:

$V=a^3$

We have a = 6cm. Substitute:

$V=6^3=216\ cm^3$

$\begin{array}{c|c}216&2\\108&2\\54&2\\27&3\\9&3\\3&3\\1\end{array}$

$216=2\cdot2\cdot2\cdot3\cdot3\cdot3=(2\cdot2)\cdot(2\cdot3)\cdot(3\cdot3)=4\cdot6\cdot9\\\\216=2\cdot2\cdot2\cdot3\cdot3\cdot3=2\cdot(2\cdot2\cdot3)\cdot(3\cdot3)=2\cdot12\cdot9\\\\216=2\cdot2\cdot2\cdot3\cdot3\cdot3=(2\cdot2\cdot2)\cdot3\cdot(3\cdot3)=8\cdot3\cdot9\\\vdots$

7 0

2 years ago

A pole-vaulter uses a 15-foot-long pile. She grips the pole so that the segment below her left hand is twice the length of the s

Shalnov [3]

Let x + 1.5 be length of segment above left hand
Let 2x be length of segment below left hand

15 = x + 1.5 + 2x
15 = 3x + 1.5
15 - 1.5 = 3x
13.5 = 3x
13.5/3= 3x/3
4.5 = x
x = 4.5
This is the length above the left hand.

2x must be then 4.5*2 = 9 foot
This is the length below the left hand.

Checking
4.5 + 9 + 1.5 = 15 foot

Adding length below left hand & length of left hand to right hand:
9 + 1.5 = 10.5
The right hand is hence 10.5 foot far up the pole.

6 0

3 years ago

. A survey of 30 students is taken. 11 students say that mathematics is their favorite subject. Based on this survey, how many s

Sveta_85 [38]

Ok, so based on a survey - you know that out of 30 students, 11 said that their favourite subject is mathematics. :-)

This means that:

11/30 of these students think mathematics if their favourite subject.

Now, in order to answer your question, we are going to have to change the denominator of the fraction above to 1000. Whatever we do to the denominator of this fraction, we must do to the numerator of this fraction.

Example:

$\frac { 11 }{ 30 } \times \frac { \frac { 1000 }{ 30 } }{ \frac { 1000 }{ 30 } } \\ \\ =\frac { \frac { 11000 }{ 30 } }{ 1000 } \\ \\ =\frac { 366.\dot { 6 } }{ 1000 }$

This means that rounded to the nearest ten, theoretically speaking, 370 students out of 1000 would say that mathematics is their favourite subject.

7 0

3 years ago

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Help pls!! Solve the inequality x + 13 < 0. Give your answer in interval notation.

kotegsom [21]

Answer:

-14

Step-by-step explanation:

x=-14+13

-1

0 is biger than -1

5 0

3 years ago

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