Question

If motor oil sells at 3 quarts for $2.83 what will 5 quarts cost

Answer 1

Answer: The correct answer is:

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" 5 [five] quarts of motor oil will cost:

→ " $ 4.72 " .

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First method of solving the problem:

Set up a ratio/proportion; in the form of an equation—using fractions— as follows:

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`(3qt)/(2.83) = (5 qt)/(x)` ; → in which we are to solve for "x" {value in "dollars".}.

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Now, let's "cross-factor multiply" the values in the equation:

3*(x) = (2.83) * 5 ;

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Now, simplify—and rewrite the equation:

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3x = 14.15 ;

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Now, divide Each side of the equation by "3" ;

to isolation "x" on one side of the equation;

& to solve for "x" ;

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3x / 3 = (14.15) / 3 ;

to get: x = 4.71666666.... (dollars);

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Let us round that number up to: "4.72" ;

{since: "4.71" ; is followed by a digit higher than "4" } ;

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The correct answer is:

→ " 5 [five] quarts of motor oil will cost: " $ 4.72 " .

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Second method of solving this problem:

1) First: We treat this problem as a "unit rate" problem;

{that is; given a numeric quantity per certain numeric value;

→ we reduce/solve for what that Particular Quantity is,

per that particular [Single] Unit numeric value.

→ For this particular problem; we are given:

$ 2.83 ["2.83 dollars"] ; per " 3 quarts " ;

We began by reducing/solving this cost (in dollars);

→ "per quart" ; [i.e. per "one quart"] ;

[i.e. per "single, unit quart"] ;

So; "
`(2.83 dollars)/(3quarts) = ((2.83)/(3)) (dollars)/(quart)` " ;

= (2.83 ÷ 3) dollars/quart ;

= 0.94333333333............. dollars per quart.

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2) Second: Then: We take that value; and to find the cost of "5 (five) quarts" (as the problem asks)—we multiply that value by "5" :

→ Using calculator:

→ 0.943333333333333333333333.... * 5 ;

= 4.7166666666.. dollars ;

→ which is the same answer obtained from the first method.

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Third method of solving the problem:

This is really just an extension of the second method directed aforementioned:

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`(2.83 dollars)/(3quarts) * (5 quarts)/(1) = ?` ;

→ The units of "quarts" cancel out; since: [" quarts/quarts = 1 "] ;

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and we have:

`((2.83) *5)/(3)` dollars ;

→ (2.83) * 5 = 14.15 ;

→
`((2.83) *5)/(3) = ((14.15))/(3)` ;

= (14.15) ÷ 3 ; = 4.716666666666 ...

→ which is the same answer from the other 2 (two) aforementioned methods.

→ Let us round that number up to: "4.72" ;

{since: "4.71" ; is followed by a digit higher than "4" } ;

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So: The correct answer is:

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" 5 [five] quarts of motor oil will cost: $ 4.72 . "

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Hope this is helpful to you! Best of luck to you!