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andrew11 [14]
4 years ago
8

William has $12.80 in coins to be deposited in the bank. There are 3 times as many quarters as nickels and 20 more dimes than ni

ckels. If n represents the number of nickels, what equation could be used to find the number of nickels to be deposited.
Mathematics
1 answer:
Natali5045456 [20]4 years ago
7 0

Let the number of nickels be = n

Let the number of dimes be = d

Let the number of quarter be = q

Total money William has = $12.80

As given, there are 3 times as many quarters as nickels

q=3n

And 20 more dimes than nickels

d=20+n

As total money is $12.80

0.05n+0.10d+0.25q=12.80

Putting the values of 'q' and 'd' to find 'n'

0.05n+0.10(20+n)+0.25(3n)=12.80

0.05n+2+0.10n+0.75n=12.80

0.90n+2=12.80

0.90n=10.80

n=12

Hence the number of nickels are = 12

If you want to also find dime and quarter, then

q=3n=3\times12=36

d=20+n=20+12=32





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-4y=8
divide both sides by -4
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sub back

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8 0
3 years ago
1. Exercise 18, section 5.4. Compute 90, 91, 92, 93, 94 and 95. Make a conjecture about the units digit of 9n where n is a posit
Burka [1]

Answer:

n is a positive integer and here 90, 91, 92, 93, 94 and 95 is 9⁰ = 1

9¹ = 9

9² = 81

9³ = 729

9⁴ = 6561

9⁵ = 59049

so mathematical induction is prove given below.

Step-by-step explanation:

9⁰ = 1

9¹ = 9

9² = 81

9³ = 729

9⁴ = 6561

9⁵ = 59049

lets us consider by P (n) for the base case n = 0 then 9⁰ = 1  So P (1) is true

k ≥ 1so consider all integers

1≤l≤ k

There is a need to prove P (k+1)

if k is odd

9^k^+^1 =9^k.9.

9^k is 9 so

9^k = 9 +10m

then

9^k^+^1 = 9 ( 9 + 10m)

       =81 + 10 (9m)

so digit is 1 and k +1 is even

3 0
3 years ago
A consumer affairs investigator records the repair cost for 4 randomly selected washers. A sample mean of $64.26 and standard de
Mashutka [201]

Answer:

Critical value: z = 1.28

The 80% confidence interval for the mean repair cost for the washers is between $46.487 and $82.033.

Step-by-step explanation:

We have that to find our \alpha level, that is the subtraction of 1 by the confidence interval divided by 2. So:

\alpha = \frac{1-0.80}{2} = 0.10

Now, we have to find z in the Ztable as such z has a pvalue of 1-\alpha

So it is z with a pvalue of 1-0.1 = 0.9, so z = 1.28

Now, find the margin of error M as such

M = z*\frac{\sigma}{\sqrt{n}}

In which \sigma is the standard deviation of the population and n is the size of the sample.

So

M = 1.28*\frac{27.77}{\sqrt{4}} = 17.773

The lower end of the interval is the mean subtracted by M. So 64.26 - 17.773 = $46.487.

The upper end of the interval is M added to the mean. So 64.26 + 17.773 = $82.033.

The 80% confidence interval for the mean repair cost for the washers is between $46.487 and $82.033.

7 0
3 years ago
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777dan777 [17]
Answer: 308in^2

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Area = 22 x 14
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4 0
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find an equation in slope intercept form for the line though point P(-3,2) and perpendicular to the line containing the two poin
CaHeK987 [17]

Answer:

y=-1/5 x +7/5

Step-by-step explanation:

First lets find the slope of the line containing the points (2,3) and (1,-2) by using the equation for slopes m1 = (y2 - y1) / (x2 - x1),

Which results in m1=5

If two lines are perpendicular, then their slopes must satisfy the following condition

m1*m2=-1

So, our new line must have the following slope (m2): m2*m1=1, if m1=5, then m2=-1/5

The line passes through P(-3,2)

Remember that the equation for a line is given by the following:

y=mx+b

if we eval P inside that equation, with m=-1/5

we have b.

2=-1/5*-3 +b

b=2-3/5

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3 years ago
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