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Kamila [148]
2 years ago
13

A class contributed $8.40 in dimes and quarters to the Red Cross. In all, there were 45 coins. How many coins of each kind were

there?
Mathematics
1 answer:
vfiekz [6]2 years ago
6 0
Let d = # of dimes
Let q = # of quarters
45 = d + q
.1d + .25q = 8.40
Then we can use the substitution method and make it so that d = 45 - q.
Then plug in the value for d into the second equation.
.1(45-q)+.25(q)=8.40
4.5-.1q+.25q=8.40
4.5+.15q = 8.40
.15q = 3.90
q = 26
d = 45 - 26 = 19
26 quarters
19 dimes
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Answer:

C. Different sample proportions would result each time, but for either sample size, they would be centered (have their mean) at the true population proportion.

Step-by-step explanation:

From the given information;

A political polling agency wants to take a random sample of registered voters and ask whether or not they will vote for a certain candidate.

A random sample is usually an outcome of any experiment that cannot be predicted before the result.

SO;

One plan is to select 400 voters, another plan is to select 1,600 voters

If the study were conducted repeatedly (selecting different samples of people each time);

Different sample proportions would result each time, but for either sample size, they would be centered (have their mean) at the true population proportion.  This is because a sample proportion deals with random experiments that cannot be predicted in advance and they  are  quite known to be centered about the population proportion.

5 0
2 years ago
What is the measure in radians for the central angle of a circle whose radius is 8 cm and intercepted arc length is 7.2 cm?
ololo11 [35]

central angle of a circle whose radius is 8 cm and intercepted arc length is 7.2 cm is 0.9 radians

Step-by-step explanation:

We need to find the central angle of a circle whose radius is 8 cm and intercepted arc length is 7.2 cm.

arc length l== 7.2 cm

radius =r= 8 cm

central angle=Ф = ?

The formula used is:

l=r\theta

Putting values:

\theta=\frac{l}{r}\\ \theta=\frac{7.2}{8} \\\theta=0.9\,\,radians

So, central angle of a circle whose radius is 8 cm and intercepted arc length is 7.2 cm is 0.9 radians

Keywords: central angle of circle

Learn more about central angle of circle at

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4 0
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Step-by-step explanation:

<u>Step 1:  Find the reasonable estimate</u>

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