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Prep 1 · Mathematics
Numbers · Arithmetic

Proportional Distributions

Before you start, make sure you know: Proportional distributions (Secondary Year 3)
Before you start, make sure you know: First-degree equations (Secondary Year 3)

Ximena, Diego, and Valeria opened a taco shop. Ximena put in $\$30{,}000$, Diego $\$50{,}000$, and Valeria $\$70{,}000$. At the end of the year they earned $\$45{,}000$. Dividing it equally among the three wouldn't be fair: whoever put in more should get more. That is a proportional distribution, and on this page you will learn to do it directly, inversely, and with two criteria at once.

Directly proportional distribution

Distributing $T$ directly proportionally to $a$, $b$, and $c$ means that the more "points" (capital, age, hours…) you have, the more you receive. Each share is worth the same for every unit of $a$, $b$, or $c$.

Bars of 2, 3, and 4 parts that join into a lower bar of 9 parts in total. 2 parts 3 parts 4 parts total: 9 parts
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Divide the amount of $9\,000$ pesos in direct proportion to the numbers $2$, $3$ and $4$.

Divide the amount of $9\,000$ pesos in direct proportion to the numbers $2$, $3$ and $4$.

Solve
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A grandfather decides to divide $2\,400$ pesos among his three grandchildren aged $8$, $10$ and $12$ in direct proportion to their ages. Determine the amount of money…

A grandfather decides to divide $2\,400$ pesos among his three grandchildren aged $8$, $10$ and $12$ in direct proportion to their ages. Determine the amount of money each receives.

Solve
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Three partners, Nerea, Beatriz and Santiago, invest $15000$ pesos, $20000$ pesos and $25000$ pesos respectively to open a business. After one year, the company generates…

Three partners, Nerea, Beatriz and Santiago, invest $15000$ pesos, $20000$ pesos and $25000$ pesos respectively to open a business. After one year, the company generates a net profit of $14400$ pesos. Calculate how much of the profit each partner receives if it is shared in direct proportion to the capital invested.

Solve

Inversely proportional distribution

Sometimes the person who has less receives more: fewer mistakes, less time, fewer absences. Then the distribution is inversely proportional.

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Divide the number $300$ into parts inversely proportional to $2$ and $3$.

Divide the number $300$ into parts inversely proportional to $2$ and $3$.

Solve
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In an athletics competition, the organisers share out a prize of $68\,000$ pesos in inverse proportion to the time taken by the top three finishers to cross the finish…

In an athletics competition, the organisers share out a prize of $68\,000$ pesos in inverse proportion to the time taken by the top three finishers to cross the finish line. If they crossed the finish line in $12$, $15$ and $20$ minutes respectively, determine the cash prize awarded to each runner.

Solve
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A grandmother wants to divide $84\,000$ pesos among her three grandchildren aged $10$, $12$ and $15$ years old. She hesitates between doing it directly proportional to…

A grandmother wants to divide $84\,000$ pesos among her three grandchildren aged $10$, $12$ and $15$ years old. She hesitates between doing it directly proportional to their ages or inversely proportional to them. Calculate how much each grandchild would receive under both options and state which grandchild experiences the greatest absolute difference in money between the two methods.

Solve

Distributions with fractions or decimals

When the coefficients are fractions or decimals, first turn them into proportional whole numbers. The distribution doesn't change.

The coefficients 1/2, 1/3, and 1/6 are multiplied by 6 and become the whole numbers 3, 2, and 1. 1/2 , 1/3 , 1/6 × 6 (LCM) 3 , 2 , 1 (whole numbers)
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Share $620$ shares in direct proportion to the fractions $\frac{1}{2}$, $\frac{1}{3}$ and $\frac{1}{5}$.

Share $620$ shares in direct proportion to the fractions $\frac{1}{2}$, $\frac{1}{3}$ and $\frac{1}{5}$.

Solve
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In a laboratory experiment, a $145$-gram sample of a chemical compound must be divided among three containers in inverse proportion to their temperatures. The…

In a laboratory experiment, a $145$-gram sample of a chemical compound must be divided among three containers in inverse proportion to their temperatures. The temperatures are $\frac{1}{2}$ ºC, $\frac{2}{3}$ ºC and $\frac{3}{4}$ ºC. Calculate the exact amount of compound that will be placed in each container.

Solve

Distributions with algebraic expressions

The method is the same when the total and the coefficients are expressions with $x$: calculate $k = \dfrac{T}{\text{sum of the coefficients}}$ and multiply. The difference is that before dividing it helps to factor out the common factor in the total, so that it simplifies with the sum of the coefficients.

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Divide the algebraic expression $N = 6x^2 + 8x$ directly proportional to the expressions $x$, $x+1$ and $x+3$. Express the three resulting parts in terms of $x$ and…

Divide the algebraic expression $N = 6x^2 + 8x$ directly proportional to the expressions $x$, $x+1$ and $x+3$. Express the three resulting parts in terms of $x$ and fully simplify the polynomials obtained.

Solve

Two criteria combined

Sometimes the distribution depends on two things: one direct and one inverse. It can also be done in two phases. In the first case, you assign each person a single coefficient: the direct factor multiplied by the reciprocal of the other.

Seniority (direct criterion) is multiplied by one over the absences (inverse criterion) and gives each person's coefficient. seniority (direct) × 1 / absences (inverse) = coefficient
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Four workers paint a building. The first works $5$ days at a rate of $6$ hours per day; the second, $4$ days at $8$ hours per day; the third, $6$ days at $5$ hours per…

Four workers paint a building. The first works $5$ days at a rate of $6$ hours per day; the second, $4$ days at $8$ hours per day; the third, $6$ days at $5$ hours per day and the fourth, $3$ days at $10$ hours per day. If they earn a total of $73\,600$ pesos and decide to share it in direct proportion to the total hours worked by each, find how much each worker will receive.

Solve
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A productivity bonus of $50\,600$ pesos is shared among three factory employees. The distribution is carried out in direct proportion to their years of service in the…

A productivity bonus of $50\,600$ pesos is shared among three factory employees. The distribution is carried out in direct proportion to their years of service in the company ($4$, $5$ and $8$ years) and in inverse proportion to the number of days absent during the year ($2$, $3$ and $4$ days). Calculate the bonus received by each employee.

Solve
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A technology company shares $1\,000\,000$ pesos of profit among three departments in two phases. In the first phase, $40$% of the total is shared directly proportional…

A technology company shares $1\,000\,000$ pesos of profit among three departments in two phases. In the first phase, $40$% of the total is shared directly proportional to the overtime hours worked: $120$, $150$ and $130$ hours. In the second phase, the remaining $60$% is shared inversely proportional to the number of technical incidents reported: $2$, $4$ and $5$ incidents. Calculate the total final profit received by each of the three departments by combining both phases.

Solve

When data is missing: algebraic setup

Often the problem doesn't give the total, but a share, a difference, or an unknown number. The key is the constant $k$ (direct) or the "share × number" constant $K$ (inverse): with the data you have, set up an equation and solve.

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In a distribution directly proportional to the quantities $3$, $5$ and $7$, the first person receives $2\,400$ pesos. Calculate the total amount shared and what the…

In a distribution directly proportional to the quantities $3$, $5$ and $7$, the first person receives $2\,400$ pesos. Calculate the total amount shared and what the other two people receive.

Solve
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An amount of money has been divided in inverse proportion to the ages of three siblings, who are $10$, $15$ and $20$ years old. If it is known that the $15$-year-old…

An amount of money has been divided in inverse proportion to the ages of three siblings, who are $10$, $15$ and $20$ years old. If it is known that the $15$-year-old sibling received $8\,000$ pesos, find the total amount shared and what the other two siblings receive.

Solve
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An amount of $174\,000$ pesos has been divided inversely proportional to three unknown numbers $A$, $B$ and $C$. The amounts received were $80\,000$ pesos, $60\,000$…

An amount of $174\,000$ pesos has been divided inversely proportional to three unknown numbers $A$, $B$ and $C$. The amounts received were $80\,000$ pesos, $60\,000$ pesos and $34\,000$ pesos respectively. Knowing that the smallest of the three original numbers is $51$, determine the value of the other two numbers.

Solve

Back to the beginning: to distribute the $\$45{,}000$ fairly among the partners, you do a distribution directly proportional to the capital: $k = \dfrac{45{,}000}{3+5+7} = 3{,}000$. Ximena receives $\$9{,}000$, Diego $\$15{,}000$, and Valeria $\$21{,}000$.

Summary

See all the exercises in this section