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Westkost [7]
3 years ago
10

Why do you cross-multiply when you solve proportions?

Mathematics
2 answers:
olga55 [171]3 years ago
4 0

Answer:

Step-by-step explanation:

since the cross multiples are equal, you find a product and use the inverse operation as you would in an equation

Example 4 is to 36 as 3 is to X: 4/36 = 3/X --> 4*X = 3*36. Divide both sides by 4, to solve for X = 27.

is over of = percent of 100

is/of=%/100

What is 10% of 40.

is = x

x/40 = 10/100

cross mulitply 40*10= 400/100=4 x=4

0

1

2

Dmitriy789 [7]3 years ago
3 0
When students cross multiply while solving a proportion, they are really multiplying both sides of the equation by the products of the two denominators. What happens is that each denominator cancels one of the factors on each side, so that it seems as if you have just crossed multiplied

Hope this helps!
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two pumps of different sizes, working together, can empty a fuel tank in 3 hours. the larger pump can empty the tank in 4 hours
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Suppose the larger pump alone can empty the tank in L hours, and the smaller pump can finish the job in S hours, then each hour the large pump empties 1/L portion of the tank, and the small pump empties 1/S per hour
Working together for three hours, they empty the whole tank, which is 100% of it, so 3/L+3/S=100%=1
Larger pump can empty the tank in 4 hours less than the smaller one, so L=S-4
replace L: 3/(S-4)+3/S=1
Make the denominator the same to solve for:
3S/[S(S-4)] +3(S-4)/[S(S-4)]=1
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8 0
3 years ago
Read 2 more answers
Which two expressions each represent 3/12
tester [92]

Answer:

1/4 or 25% Your Welcome!

7 0
3 years ago
Scientist are studying a bacteria sample. The function f(x)=360(1.07)^x gives the number of bacteria in the sample at the end of
Lapatulllka [165]

Options :

A. The initial number of bacteria is 7.

B. The initial of bacteria decreases at a rate of 93% each day.

C. The number of bacteria increases at a rate of 7% each day.

D. The number of bacteria at the end of one day is 360.

Answer:

C. The number of bacteria increases at a rate of 7% each day.

Step-by-step explanation:

Given the function :

f(x)=360(1.07)^x ; Number of bacteria in sample at the end of x days :

The function above represents an exponential growth function :

With the general form ; Ab^x

Where A = initial amount ;

b = growth rate

x = time

For the function :

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b = growth rate = (1 + r) = 1.07

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1 + r = 1.07

r = 1.07 - 1

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r as a percentage ;

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Solution:
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