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3 years ago

a dvd costs twice as much as a music cd. Jack buys 2 dvds and 2 cds and spends $45. Determine how much one cd costs. in dollars

2 answers:

4 0

V=2c, and 2v + 2c =45 you can substitute v for 2c in the second equation because they equal to get 4c +2c =45 6c =45 c = 45/6, so the answer is $7.50

VMariaS [17]3 years ago

3 0

$dvd=d \\ cd=c \\ \\ \left \{ {{d=2c} \atop {2d+2c=45}} \right. \\ \\ 2(2c)+2c=45 \\ 4c+2c=45 \\ 6c=45 \\ c=7.5 \\ \\ d=2(7.5) \\ d=15$

One CD costs $7.50.
One DVD costs $15.00.

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In a certain clinical study, 15% of participants were classified as heavy smokers, 25% as light-smokers, and the rest as non-smo

Natasha_Volkova [10]

Answer:

There is a 28.57% probability that a randomly selected participant who died by the end of the study was a non-smoker.

Step-by-step explanation:

We have the following probabilities:

A 15% probability that a participant is classified as a heavy smoker.

A 25% probability that a participant is classified as a light smoker.

A 100% - 25% - 15% = 60% probability that a participant is classified as a non smoker.

A x% probability that a non smoker dies.

A 3x% probability that a light smoker dies.

A 5x% probability that a heavy smoker dies.

This can be formulated as the following problem:

What is the probability of B happening, knowing that A has happened.

It can be calculated by the following formula

$P = \frac{P(B).P(A/B)}{P(A)}$

Where P(B) is the probability of B happening, P(A/B) is the probability of A happening knowing that B happened and P(A) is the probability of A happening.

This problem is:

What is the probability of the participant being a non-smoker, given that he died?

P(B) is the probability that the participant is a non smoker. So

$P(B) = 0.6$

P(A/B) is the probability that the participant dies, given that he is a non smoker. So:

$P(A/B) = x$

P(A) is the probability that the participant dies:

$P(A) = P_{1} + P_{2} + P_{3}$

$P_{1}$ is the probability that a heavy smoker is selected and that he dies. So:

$P_{1} = 0.15*5x = 0.75x$

$P_{2}$ is the probability that a light smoker is selected and that he dies. So:

$P_{2} = 0.25*3x = 0.75x$

$P_{3}$ is the probability that a non-smoker is selected and that he dies. So:

$P_{3} = 0.60*x = 0.60x$

The probability that a participant dies is:

$P(A) = P_{1} + P_{2} + P_{3} = 0.75x + 0.75x + 0.60x = 2.10x$

The probability of the participant being a non-smoker, given that he died, is:

$P = \frac{P(B).P(A/B)}{P(A)} = \frac{0.6x}{2.10x} = \frac{0.6}{2.10} = 0.2857$

There is a 28.57% probability that a randomly selected participant who died by the end of the study was a non-smoker.

7 0

3 years ago

Y= -3x^2-24x-46 write in vertex form

mario62 [17]

ANSWER

$y= -3{(x + 4)}^{2} + 2$

EXPLANATION

The given function is:

$y= -3x^2-24x-46$

Factor -3 for the first 2 terms.

$y= -3(x^2 + 8x)-46$

We add and subtract the square of the coefficient of x.

$y= -3(x^2 + 8x + {(4)}^{2} ) - - 3( {4)}^{2} -46$

Factor the perfect square trinomial.

$y= -3 {(x + 4)}^{2} ) + 48 -46$

The vertex form is:

$y= -3{(x + 4)}^{2} + 2$

6 0

3 years ago

The volume of a can is 8.50 m' Express this volume in (a)cm^3, (b)ft^3, (c)in^3.

jeyben [28]

Answer:

$(tex)2)240 = 15n( |tex)$

7 0

3 years ago

Find the coordinates of the midpoint, S of RT given: R(3,0) and T(2, 1).

mihalych1998 [28]

if the distance from R to S is only half then the other half is S to T. The distance between R and S is (5,2). that should give you the answer

3 0

2 years ago

Read 2 more answers

Three siblings- Kate, Sarah, and Dave- committed themselves to volunteer 160 hours for a homeless charity to build new housing .

liraira [26]

Kate worked for 50 hours, Dave worked for 65 hours and Sarah

worked for 45 hours

Step-by-step explanation:

Three siblings- Kate, Sarah, and Dave- committed themselves to

volunteer 160 hours for a homeless charity to build new housing

1. Dave worked 15 hours more than Kate

2. Sarah worked 5 hours fewer than Kate

3. The total hours for them is 160 hours

Assume that Kate worked for x hours

∵ Kate worked for x hours

∵ Dave worked 15 hours more than Kate

∴ Dave worked for x + 15 hours

∵ Sarah worked 5 hours fewer than Kate

∴ Sarah worked x - 5 hours

∵ They worked for 160 hours

- Add the number of worked hours of them and equate the sum

by 160

∴ x + x + 15 + x - 5 = 160

- Add like terms in the left hand side

∴ 3x + 10 = 160

- Subtract 10 from both sides

∴ 3x = 150

- Divide both sides by 3

∴ x = 50 hours

∵ Kate worked for x hours

∴ Kate worked for 50 hours

∵ Dave worked for x + 15 hours

∴ Dave worked for 50 + 15 = 65 hours

∵ Sarah worked for x - 5 hours

∴ Sarah worked for 50 - 5 = 45 hours

Kate worked for 50 hours, Dave worked for 65 hours and Sarah

worked for 45 hours

Learn more:

You can learn more about equation in brainly.com/question/11229113

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6 0

3 years ago