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Scilla [17]
3 years ago
6

A jar of coins has only dimes and quarters in it. Combined there are a total of 120 coins. The total of all the coins is $25.65.

How many dimes and quarters are there?
Mathematics
1 answer:
torisob [31]3 years ago
5 0
<h2>Steps</h2>

So for this, we will create a system of equations. With our information, this is our system (let x = dimes and y = quarters):

x+y=120\\0.10x+0.25y=25.65

So with this system, I will be using the substitution method. With the first equation, subtract y on both sides of the equation:

x=120-y\\0.10x+0.25y=25.65

Now, since we know that x = 120 - y, substitute that into the second equation and solve for y as such:

0.10(120-y)+0.25y=25.65\\12-0.10y+0.25y=25.65\\12+0.15y=25.65\\0.15y=13.65\\y=91

Now that we have the value of y, substitute it into either equation to solve for x:

x+91=120\\x=29\\\\0.10x+0.25(91)=25.65\\0.10x+22.75=25.65\\0.10x=2.90\\x=29

<h2>Answer</h2>

<u>In short, there are 29 dimes and 91 quarters.</u>

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Step-by-step explanation:

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For the alternative hypothesis,

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We would determine the test statistic which is the z score

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The difference between sample proportion and population proportion(p - P) is 0.51 - 0.35 = 0.16

Since the curve is symmetrical and it is a two tailed test, the p for the left tail is 0.51 - 0.16 = 0.35

the p for the right tail is 0.51 + 0.16 = 0.67

These proportions are lower and higher than the null proportion. Thus, they are evidence in favour of the alternative hypothesis. We will look at the area in both tails. Since it is showing in one tail only, we would double the area

From the normal distribution table, the area below the test z score in the left tail is < 0.00001

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Since alpha, 0.01 > than the p value, then we would reject the null hypothesis.

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Answer:

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