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damaskus [11]
3 years ago
15

The variables y and x have a proportional relationship, and y = 5 when x = 4.

Mathematics
1 answer:
MrRissso [65]3 years ago
3 0

If the variables y and x have a proportional relationship, we have

xy=k

Since (x,y)=(4,5) is a valid pair, we know that

xy=20

So, if y = 8, we have

8x=20 \iff x=\dfrac{20}{8}=\dfrac{5}{2}

You might be interested in
Is 2/3 equal to 2/4 because the numerator are equal
Masja [62]
No. For fractions to be equal, both the numerators and denominators have to be proportional.

Since both denominators are 2, the denominators would have to be just 3 or just 4.
5 0
3 years ago
Reverse the two digits of my age, divide by three, add 20, and the result is my age. How many years old am I
lapo4ka [179]

Answer:

  • 48 years old.

Step-by-step explanation:

Let the age be xy or 10x + y.

Reverse the two digits of my age, divide by three, add 20, and the result is my age, convert this to equation:

  • (10y + x)/3 + 20 = 10x + y
  • (10y + x)/3 = 10x + y - 20
  • 10y + x = 3(10x + y - 20)
  • 10y + x = 30x + 3y - 60
  • 30x - x + 3y - 10y = 60
  • 29x - 7y = 60

We should consider both x and y are between 1 and 9 since both the age and its reverse are 2-digit numbers.

Possible options for x are:

  • 29x ≥ 7*1 + 60 = 67 ⇒ x > 2, at minimum value of y,

and

  • 29x ≤ 7*9 + 60 = 123 ⇒ x < 5, at maximum value of y.

So x can be 3 or 4.

<h3>If x = 3</h3>

  • 29*3 - 7y = 60
  • 87 - 7y = 60
  • 7y = 27
  • y = 27/7, discarded as fraction.

<h3>If x = 4</h3>

  • 29*4 - 7y = 60
  • 116 - 7y = 60
  • 7y = 56
  • y = 8

So the age is 48.

6 0
1 year ago
Find the height of a triangle in which base is 25cm and<br> area is 200cm2.
Arisa [49]

Answer:

16

Step-by-step explanation:

(200*2)/25=16

4 0
3 years ago
Determine the truth value of each statement based on the expression.
meriva
1. true
2. false
3. true
4. false
5. true
3 0
3 years ago
How long will it take to have R30 000 for a trip to Europe if I invest R20 000 now at 15% per year, compounded quarterly?
maw [93]

<span>Compound  interest  formula</span>

A=P(1+ \frac{r}{n} )^{nt}

 

Where

<span>
A= Future value
P = the Principal (the initial amount of money) 
r = annual interest rate</span>

t = time

<span>n= number of times compounded in one t






Remark
----------------------------------------------------------------------------------

r is generally a percentage like 3%, 7% etc and are applied in the formula as 0.03, 0.07..., 

the interest is compounded generally annually (n=1), quarterly (n=4), monthly (n=12), etc...

t is in years,


In our problem:

</span>

A= 30 000

P =20 000

r = 15%=0.15

time = t = ?

n= 4

applying the formula:

A=P(1+ \frac{r}{n} )^{nt}\\\\30,000=20,000(1+ \frac{0.15}{4} )^{4t}\\\\ \displaystyle{\frac{30,000}{20,000} =(1.0375)^{4t}

\displaystyle{ 1.5={(1.0375^4)}^t\\\\

1.5=1.159^t\\\\ \displaystyle { t=log_{1.159}1.5=2.75

75% of 12 months is 3/4 of 12 months, which is 9 months

Answer: 2 years, 9 months

3 0
3 years ago
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