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Darina [25.2K]
4 years ago
9

a box contains 20 marbles, 12 red and 8 blue. What is the probability for picking a blue marble and after replacing it picking a

red marble​
Mathematics
1 answer:
Amanda [17]4 years ago
7 0

Answer:

\frac{6}{25}

Step-by-step explanation:

Probability of an event can be formed from the fraction where the numerator is  the number of desired outcomes and the denominator is the number of total outcomes.  In this case, there are 20 marbles, so 20 total outcomes.  The desired outcome is first picking a blue, replacing it, and then picking a red.  Since you are replacing the marble, these events are independent, which means that they don't rely on previous events and the probability of picking a red or blue is the same each time:

\frac{blue}{marbles}=\frac{8}{20}=\frac{2}{5}

\frac{red}{marbles}=\frac{12}{20}=\frac{3}{5}

When we combine independent events, we multiply the probabilities:

\frac{2}{5}*\frac{3}{5}=\frac{6}{25}

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Stels [109]

Answer: 7/8

Step-by-step explanation:

The easiest way to do this is to find a common denominator, so first we find out 2 times how much equals 8? 2x4 = 8. So with 8 being our common denominator, we have to multiple 4 to every number in the fraction 1/2. So 1x4 = (4/8) = 2x4. Then you just add the top numbers, so 4 + 3 = 7 and keep the denominator. 7/8.

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3 years ago
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Which statement compares the two numbers correctly?
AVprozaik [17]

Answer:

A

Step-by-step explanation:

Six hundred seventy-two thousandths = 0.672

0.672 < 0.8

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3 years ago
Suppose that we wish to assess whether more than 60 percent of all U.S. households in a particular income class bought life insu
IceJOKER [234]

Answer:

A. 0.0049

B. Yes

Step-by-step explanation:

Sample proportion = 0.64

N = 1000

Population proportion = 0.60

We solve for standard deviation

= √p(1-p)/n

= √0.60(1-0.60)/1000

= √0.60x0.40/1000

= √0.00024

= 0.0155

A.

The probability of sample >=0.64

Z>=0.64-0.60/0.0155

Z >= 0.04/0.0155

So z >= 2.5806

Using excel this equal to 0.0049

0.0049 is probability of sample proportion being 0.64 at least.

B.

This answer in a shows that than 60% of households in the united states income class purchased life insurance last year.

3 0
3 years ago
Ella has 0.5 lb of sugar. how much water should she add to make the following concentrations? Tell Ella how much syrup she will
makkiz [27]

Answer:

For 50% syrup, add 0.5 lb of water for 1 lb of syrup; for 5% syrup, add 9.5 lb of water for 10 lb of syrup; for 75% syrup, add 0.17 lb of water for 0.67 lb of syrup; for 1.5% syrup, add 32.8 lb of water for 33.3 lb of syrup.

Step-by-step explanation:

Let x represent the amount of water added.  This means the total mass of the syrup is represented by 0.5+x.

To find percentages, we divide the part by the whole.  For a 50% syrup, we need the part (sugar) compared to the whole (sugar + water) to equal 50%, or 0.50:

Multiply both sides by 0.5+x:

Using the distributive property, we have

0.5 = 0.5(0.5)+0.5(x)

0.5 = 0.25+0.5x

Subtract 0.25 from each side:

0.5-0.25 = 0.25+0.5x-0.25

0.25 = 0.5x

Divide both sides by 0.5:

0.25/0.5 = 0.5x/0.5

x = 0.5

For 50% syrup, add 0.5 lb of water.  This makes the total mass 0.5+0.5 = 1 lb.

For 5% syrup, we change the equation to equal 0.05 (5% = 5/100 = 0.05) and leave everything else the same:

Multiply both sides by 0.5+x:

Using the distributive property,

0.5 = 0.05(0.5)+0.05(x)

0.5 = 0.025 + 0.05x

Subtract 0.025 from both sides:

0.5-0.025 = 0.025+0.05x-0.025

0.475 = 0.05x

Divide both sides by 0.05:

0.475/0.05 = 0.05x/0.05

x = 9.5

For 5% syrup, add 9.5 lb of water; the total mass will be 9.5+0.5 = 10 lb.

For 75% syrup, set the equation equal to 0.75:

Using the distributive property,

0.5 = 0.75(0.5)+0.75(x)

0.5 = 0.375 + 0.75x

Subtract 0.375 from each side:

0.5 - 0.375 = 0.375 + 0.75x - 0.375

0.125 = 0.75x

Divide both sides by 0.75:

0.125/0.75 = 0.75x/0.75

0.17 = x

For 75% syrup, add 0.17 lb of water; the total mass is 0.17+0.5 = 0.67 lb.

For 1.5% syrup, set the equation equal to 0.015:

Using the distributive property,

0.5 = 0.015(0.5) + 0.015(x)

0.5 = 0.0075 + 0.015x

Subtract 0.0075 from each side:

0.5-0.0075 = 0.0075 + 0.015x - 0.0075

0.4925 = 0.015x

Divide both sides by 0.015:

0.4925/0.015 = 0.015x/0.015

32.8 = x

For 1.5% syrup, use 32.8 lb of water; the total mass is 32.8+0.5 = 33.3 lb.

I hope this is right and have a good day

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Answer:

The least common denominator of the fraction is 14

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