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3 years ago

Sam has $3.30 in quarters and dimes, and the total number of coins is 18. How many quarters and how many dimes?

Mathematics

1 answer:

zhuklara [117]3 years ago

4 0

Answer:

Quarters: 10

Dimes: 8

Step-by-step explanation:

Constraints

value: 0.25q + 0.10d = 3.30

count: q + d = 18

q = 18 - d

0.25(18-d) + 0.10d = 3.30

4.50-0.25d+0.10d = 3.30

4.50-0.15d = 3.30

-0.15d = -1.20

d = 8

q + d = 18

q + 8 = 18

q = 10

Check:

0.25(10) + 0.10(8) = 3.30

2.5+ 0.80 = 3.30

3.30 = 3.30

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Random samples of size 81 are taken from an infinite population whose mean and standard deviation are 200 and 18, respectively.

TiliK225 [7]

Answer:

d. 200 and 2

Step-by-step explanation:

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$ .

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

In this problem, we have that:

Mean = 200

Standard deviation = 18

Sample size: 81

Standard error: $s = \frac{18}{\sqrt{81}} = 2$

So the correct answer is:

d. 200 and 2

7 0

3 years ago

Read 2 more answers

Help with number 3 and 4 im stuck

Sonbull [250]

1.5,1.25,1.75,3.5 for number 3

8 0

3 years ago

The scores on a psychology exam were normally distributed with a mean of 57

olya-2409 [2.1K]

Answer:

Cutoff for a failing score is 49 and 2.28% students failed.

Step-by-step explanation:

We have been given that scores on a psychology exam were normally distributed with a mean of 57 and a standard deviation of 4.

2 standard deviation below mean would be,

$57-2(4) =57-8= 49$

Therefore,Cutoff far a failing score is 49.

Now let us find out the z-score for our given values,

$z=\frac{x-\mu}{\sigma}$

$z=\frac{49-57}{4}=\frac{-8}{4} =-2$

Now let us look up the probability from normal distribution table.

$P(z$

Therefore, percentage of students failed is 2.28%.

3 0

3 years ago

. A rectangular garden will be divided into two plots by fencing it on the diagonal. The diagonal distance from one corner of th

ASHA 777 [7]

Answer:

Step-by-step explanation:

The width = x

The length of the garden is three times the width => the length = 3x

The diagonal distance is five yards longer than the width=> the width=x+5

pythagorean theorem:

$(x+5)^{2} = 3x^{2} +x^{2} \\=> x +5 = \sqrt{( 3x)^{2} +x^{2}} \\=> x+5= \sqrt{10x^{2} } \\=>x+5= \sqrt{10} x\\=> \sqrt{10} x - x=5\\=> x= \frac{5+5\sqrt{10} }{9} (yd)\\\\ the diagonal = x+5 = \frac{5+5\sqrt{10} }{9} +5= \frac{50+5\sqrt{10} }{9} (yd)$

My English is not too good but I hope you will understand.

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2 years ago

What value should she use as the common ratio 0.05

pychu [463]

Answer:0.50

Step-by-step explanation:

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