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elena55 [62]
3 years ago
13

Billy had some $2 and $10 notes. The total value of the notes was $864. She exchanged 5 $10 notes into $2 notes. The number of $

2 notes and $10 notes were equal in the end. How many $2 notes did he have at first?
Mathematics
1 answer:
Sergio039 [100]3 years ago
6 0

Answer:

7

Step-by-step explanation:

because 10 x 5 +50 and when u subtract that from 864 there 814 left and 800 can be divided by 10. Therefore 14/ 2 =7 idk if this is right tho

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When an opinion poll selects cell phone numbers at random to dial, the cell phone exchange is first selected and then random dig
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Answer:

A

Step-by-step explanation:

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6 0
3 years ago
Find all solutions of the equation in the interval [0, 2π). (enter your answers as a comma-separated list. if there is no soluti
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0, π/2, π, 3π/2
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5 0
3 years ago
A random sample of 20 students yielded a mean of ¯x = 72 and a variance of s2 = 16 for scores on a college placement test in mat
Helen [10]

Answer:

The 98% confidence interval for the variance in the pounds of impurities would be 8.400 \leq \sigma^2 \leq 39.827.

Step-by-step explanation:

1) Data given and notation

s^2 =16 represent the sample variance

s=4 represent the sample standard deviation

\bar x represent the sample mean

n=20 the sample size

Confidence=98% or 0.98

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population mean or variance lies between an upper and lower interval".  

The margin of error is the range of values below and above the sample statistic in a confidence interval.

The Chi square distribution is the distribution of the sum of squared standard normal deviates .

2) Calculating the confidence interval

The confidence interval for the population variance is given by the following formula:

\frac{(n-1)s^2}{\chi^2_{\alpha/2}} \leq \sigma^2 \leq \frac{(n-1)s^2}{\chi^2_{1-\alpha/2}}

On this case the sample variance is given and for the sample deviation is just the square root of the sample variance.

The next step would be calculate the critical values. First we need to calculate the degrees of freedom given by:

df=n-1=20-1=19

Since the Confidence is 0.98 or 98%, the value of \alpha=0.02 and \alpha/2 =0.01, and we can use excel, a calculator or a table to find the critical values.  

The excel commands would be: "=CHISQ.INV(0.01,19)" "=CHISQ.INV(0.99,19)". so for this case the critical values are:

\chi^2_{\alpha/2}=36.191

\chi^2_{1- \alpha/2}=7.633

And replacing into the formula for the interval we got:

\frac{(19)(16)}{36.191} \leq \sigma^2 \leq \frac{(19)(16)}{7.633}

8.400 \leq \sigma^2 \leq 39.827

So the 98% confidence interval for the variance in the pounds of impurities would be 8.400 \leq \sigma^2 \leq 39.827.

7 0
3 years ago
Find the product of 543.1187 and 100 A. 5.431187 B. 54,311.87 C. 5,431.187 D. 54.31187 Can someone also explain how they came up
Katyanochek1 [597]
543.1187\times100=\boxed{54311.87}

When you're multiplying by a power of 10 such as 100, the decimal point moves two places to the right. Note that this corresponds with the number of zeroes in 100. Of course our number is going to get bigger, not smaller, which means we'd have to be going right. If we multiplied by something like 0.001, we'd also be going two places, just going smaller and to the left.
7 0
3 years ago
Read 2 more answers
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