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Question

The total population of a town is 50,000. The number of males and females increases by 10% and 15% respectively and consequently the population of the town becomes 56,000. What was the number of males in the town?

The correct answer is
30,000

Population Growth Calculation

Let the initial number of males be represented by M and the initial number of females by F.

Initial Population Setup

  • Total initial population: $M + F = 50,000$

Population Growth Details

  • Males increase by 10%, so the new male population is $M + 0.10M = 1.10M$.
  • Females increase by 15%, so the new female population is $F + 0.15F = 1.15F$.
  • The final total population is given as 56,000.

Therefore, the equation for the final population is: $1.10M + 1.15F = 56,000$

Solving for Initial Males

We have a system of two linear equations:

  1. $M + F = 50,000$
  2. $1.10M + 1.15F = 56,000$

From equation (1), express $F$ in terms of $M$: $F = 50,000 - M$

Substitute this expression for $F$ into equation (2): $1.10M + 1.15(50,000 - M) = 56,000$

Distribute and simplify:

  • $1.10M + 57,500 - 1.15M = 56,000$
  • Combine the terms with $M$: $-0.05M + 57,500 = 56,000$

Isolate the term with $M$: $-0.05M = 56,000 - 57,500$ $-0.05M = -1,500$

Solve for $M$: $M = \frac{-1,500}{-0.05}$ $M = 30,000$

The initial number of males in the town was 30,000.

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Important Questions from Percentage (Notes)

  1. Anubhav spent 14% of his income on electricity bills, 28% on rent and 18% on shopping. If $\frac{1}{4}$ th of the remaining amount is ₹5120, how much did he spend on electricity bills ?
  2. Gokul donates $17\%$ of his savings to old age home, $17\%$ of the savings to orphanage and $17\%$ of his savings to foundations for medical help. The remaining amount of Rs.$9800$ of savings is been deposited in bank. Find the salary of Gokul, if $50\%$ of the salary is his savings amount. (In Rs.)
  3. Which of the following multipliers will increase a given number by 25.3 % ?
  4. If A earns \(33\frac{1}{3}%\) more than B, then how much percent does B earn less than A?

  5. A mobile phone with a marked price ₹16,800 was sold for ₹13,944. What is the percentage discount given on the sale of the mobile phone.
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