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valentinak56 [21]
3 years ago
8

Ralph is 3 times as old as Sara. In 6 years , Ralph will be only twice as old as Sara will be then. Find Ralph’s age now .

Mathematics
1 answer:
Delvig [45]3 years ago
3 0

Answer:

Ralph's current age is 18.

Step-by-step explanation:

Let r and s represent the current ages of Ralph and Sara respectively.  Our task here is to determine r, Ralph's age now.

If Ralph is 3 times as old as Sara now, then r = 3s.

Six years from now, Ralph's age will be r + 6 and Sara's will be s + 6.  Ralph will be only twice as old as Sara will be then.  This can be represented algebraically as

r + 6 = 2(s + 6).

We now have the following system of linear equations to solve:

r + 6 = 2s + 12, or r - 2s = 6, and r = 3s (found earlier, see above).

r - 2s = 6

r = 3s

Substituting 3s for r in r - 2s = 6, we get 3s = 2s + 6, or s = 6.  Sara is 6 years old now, meaning that Ralph is 3(6 years), or 18 years old.

Ralph's current age is 18.


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Arlecino [84]

No, it is not. I will show you:

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6 0
4 years ago
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Given two dependent random samples with the following results:
Naddik [55]

Answer:

The null hypothesis will not be rejected.

Step-by-step explanation:

The hypothesis for the test is:

<em>H</em>₀: There is no difference between the two population means, i.e. <em>d</em> = 0.

<em>Hₐ</em>: There is a significant difference between the two population means, i.e. <em>d</em> ≠ 0.

Consider the Excel output attached.

The mean of the differences is, \bar d=-2.75.

The standard deviation of the differences is, S_{d}=4.268.

Compute the test statistic as follows:

t=\frac{\bar d}{S_{d}/\sqrt{n}}=\frac{-2.75}{4.268/\sqrt{8}}=-1.82

The degrees of freedom is, n - 1 = 7.

Compute the <em>p</em>-value as follows:

p-value=2\cdot P(t_{7}

The decision rule is:

The null hypothesis will be rejected if the p-value of the test is less than the significance level.

<em>p</em>-value = 0.112 > α = 0.02.

The null hypothesis will not be rejected.

4 0
4 years ago
The spending limit on John’s credit card is given by the function f(x)=15,000+1.5x , where x is his monthly income. f^-1x . The
Katena32 [7]
<span>1.
"The spending limit on John’s credit card is given by the function f(x)=15,000+1.5x"

means that if the monthly income of John is $ 5,000 ,he can spend at most 

f(5,000)=15,000+1.5*5,000=15,000+ 7,500=22, 500 (dollars)

Or for example

if Johns monthly income is $8,000, then he can spend at most

 </span>f(8,000)=15,000+1.5*8,000=15,000+ 12,000=27,000 (dollars)<span>


2.
Now, assume that the maximum amount that John can spend is y.

Then, y=15,000+1.5x

we can express x, the monthly income, in terms of y by isolating x:

</span>y=15,000+1.5x
<span>
1.5x = y-15,000


</span>x= \frac{y-15,000}{1.5}
<span>
thus, in functional notation, x, the monthly income, is a function , say g, of variable y, the max amount:

</span>x=g(y)=\frac{y-15,000}{1.5}

since we generally use the letter x for the variable of a function, we write g again as:

g(x)=\frac{x-15,000}{1.5}
<span>
for example :

</span>g(50,000)=\frac{50,000-15,000}{1.5}= \frac{35,000}{1.5}= 23,333
<span>
tells us that if the maximum amount that John can spend is 50,000 $, then his monthly income is 23,333 $.

3.

If John's limit is $60,000, his monthly income is 

</span>g(60,000)=\frac{60,000-15,000}{1.5}= \frac{45,000}{1.5}=30,000<span>
 dollars.


Answer: $ 30,000

Remark: g is called the inverse function of f, since it undoes what f does.

instead of g(x), we could use the notation </span>f ^{-1}(x)<span>



</span>
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KonstantinChe [14]
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Match each justification to its corresponding step in the following solution. (Table shown above)
AveGali [126]

Answer:

D

Step-by-step explanation:

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