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Mila [183]
3 years ago
14

At a local preschool, there is a ratio of 3 boys to every 4 girls. If there are 245 total preschoolers enrolled, how many boys a

re there
Mathematics
1 answer:
Zarrin [17]3 years ago
8 0

A ratio can be written in three different ways: 3 to 4, 3:4, and 3/4

What does this mean? It means that for every group of 7 students (3+4) there are 3 boys and 4 girls. And how many groups do we have? We have:

245/7= 35 We have 35 groups, and we just said that each group has 3 boys and 4 girls:

35*3= 105 boys

35*4= 140 girls

_ _ _---------

Total: 245 students

-------------------------------------

Here's how to set up an equation:

Let's call the number of girls x. Since the total is 245 students, 245-x= boys:

 

Set up the equation by writing the number of students in the ratio as a fraction:

3/4= (245-x)/x Cross multiply:

3x= 4(245-x) Multiply on right:

3x= 980-4x Add 4x on both sides:

7x= 980 Divide both sides by 7:

x= 140 this is how many girls there are. And:

245-140= 105= boys

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2 years ago
MATH HELP PLEASE!!! PLEASE HELP!!!
grandymaker [24]
The answer is:  [C]:  " f(c) = \frac{9}{5} c  + 32 " .
________________________________________________________

Explanation:

________________________________________________________
Given the original function:  

" c(y) = (5/9) (x <span>− 32) " ; in which "x = f" ; and "y = c(f) " ;
________________________________________________________
</span>→  <span>Write the original function as:  " y = </span>(5/9) (x − 32) " ; 

Now, change the "y" to an "x" ; and the "x" to a "y"; and rewrite; as follows:
________________________________________________________
    x = (5/9) (y − 32) ; 

Now, rewrite THIS equation; by solving for "y" ; in terms of "x" ; 
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→ That is, solve this equation for "y" ; with "c" as an "isolated variable" on the
 "left-hand side" of the equation:

We have:

→  x  =  " (  \frac{5}{9}  ) * (y − 32) " ;

Let us simplify the "right-hand side" of the equation:
_____________________________________________________

Note the "distributive property" of multiplication:
__________________________________________
a(b + c) = ab + ac ;  <u><em>AND</em></u>:

a(b – c) = ab – ac
.
__________________________________________

As such:
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" (\frac{5}{9}) * (y − 32) " ; 

=  [ (\frac{5}{9}) * y ]   −  [ (\frac{5}{9}) * (32) ] ; 


=  [ (\frac{5}{9}) y ]  − [ (\frac{5}{9}) * (\frac{32}{1})" ;

=  [ (\frac{5}{9}) y ]  − [ (\frac{(5*32)}{(9*1)} ] ; 

=  [ (\frac{5}{9}) y ]  −  [ (\frac{(160)}{(9)} ] ; 

= [ (\frac{5y}{9}) ]  −  [ (\frac{(160)}{(9)} ] ; 

= [ \frac{(5y-160)}{9} ] ;  
_______________________________________________
And rewrite as:  

→  " x  =  \frac{(5y-160)}{9} "  ;

We want to rewrite this; solving for "y";  with "y" isolated as a "single variable" on the "left-hand side" of the equation ;

We have:

→  " x  =  \frac{(5y-160)}{9} "  ; 

↔  " \frac{(5y-160)}{9} = x ; 

Multiply both sides of the equation by "9" ; 

 9 * \frac{(5y-160)}{9}  =  x * 9 ; 

to get:

→  5y − 160 = 9x ; 

Now, add "160" to each side of the equation; as follows:
_______________________________________________________

→  5y − 160 + 160 = 9x + 160 ; 

to get:

→  5y  =  9x + 160 ; 

Now,  divided Each side of the equation by "5" ; 
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→  5y / 5  = (9y + 160) / 5 ; 

to get: 
 
→  y = (9/5)x + (160/5) ; 

→  y =  (9/5)x + 32 ; 

 →  Now, remember we had substituted:  "y" for "c(f)" ; 

Now that we have the "equation for the inverse" ;
     →  which is:  " (9/5)x  + 32" ; 

Remember that for the original ("non-inverse" equation);  "y" was used in place of "c(f)" .  We have the "inverse equation";  so we can denote this "inverse function" ; that is, the "inverse" of "c(f)" as:  "f(c)" .

Note that "x = c" ; 
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So, the inverse function is: "  f(c) = (9/5) c  + 32 " .
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 →  which is:  

→  Answer choice:  [C]:  " f(c) = \frac{9}{5} c  + 32 " .
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Answer:

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Step-by-step explanation:

x+y=18

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Given:

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Number of violinists in the school orchestra = 21

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The combined number of cellists and violinists.

Solution:

Let the number of violinists and cellists in the school orchestra are 7x and 3x respectively.

Then, combined number of cellists and violinists is

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Divide both sides by 7.

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Now, the combined number of cellists and violinists is

\text{Combined number of cellists and violinists}=10(3)    [Using (i)]

\text{Combined number of cellists and violinists}=30

Therefore, the combined number of cellists and violinists is 30.

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