Percentage All Competence Aptitude

Percentage All Competence Aptitude
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Question 121

The population of a village has increased annually at the rate of 25%. If at the end of 3 years it is 10,000, the population in the beginning of the first year was ?

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Let's denote the present value of the scooter as \(P\). According to the given information, the value of the scooter decreases by 10% each year.

The value of the scooter after 1 year (\(P_1\)) can be calculated as:\[ P_1 = P - 0.10P = 0.90P \]

After the second year, the value (\(P_2\)) becomes:\[ P_2 = 0.90P - 0.10(0.90P) = 0.81P \]

After the third year, the value (\(P_3\)) becomes:\[ P_3 = 0.81P - 0.10(0.81P) = 0.729P \]

Now, we know the present value \(P\) is Rs. 7,290. Let's substitute this value into the equation:

\[ 0.729P = 7290 \]

Now, solve for \(P\):

\[ P = \dfrac{7290}{0.729} \]

\[ P = 10000 \]

Therefore, the value of the scooter 3 years back was Rs. 10,000. Hence, the correct answer is Rs. 10,000.

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Question 122

Raman’s salary is increased by 5% this year. If his present salary is 1,806, the last year’s salary was ?

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Let Raman's last year's salary be denoted by \(X\).

According to the given information, Raman's salary is increased by 5% this year, so the present salary (\(P\)) is given by:

\[ P = X + 0.05X = 1.05X \]

Now, we are given that Raman's present salary is \(1,806\). Substitute this value into the equation:

\[ 1.05X = 1,806 \]

Now, solve for \(X\):

\[ X = \dfrac{1,806}{1.05} \]

\[ X \approx 1,720 \]

Therefore, Raman's last year's salary was approximately \(1,720\). Hence, the correct answer is \(1,720\).

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Question 123

The value of a property decreases every year at the rate of 5%. If its present value is 4,11,540, what was its value 3 years ago ?

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Let's denote the present value of the property as \(P\).

After the first year, the value (\(P_1\)) becomes:\[ P_1 = P - 0.05P = 0.95P \]

After the second year, the value (\(P_2\)) becomes:\[ P_2 = 0.95P - 0.05(0.95P) = 0.9025P \]

After the third year, the value (\(P_3\)) becomes:\[ P_3 = 0.9025P - 0.05(0.9025P) = 0.857375P \]

Given that the present value is \(4,11,540\):

\[ P_3 = 0.857375P = 4,11,540 \]

Now, solve for \(P\):

\[ P = \dfrac{4,11,540}{0.857375} \]

\[ P \approx 4,80,000 \]

Therefore, the value of the property 3 years ago was approximately \(4,80,000\). Hence, the correct answer is \(4,80,000\).

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Question 124

The present population of a city is 180000. If it increases at the rate of 10% per annum, its population after 2 years will be ?

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To calculate the population after 2 years with a 10% annual increase, we can use the formula for compound interest:

\[ \text{Future Population} = \text{Present Population} \times (1 + \text{Rate})^{\text{Time}} \]

Given:
- Present Population = 180,000
- Rate of increase = 10% or 0.10 (as a decimal)
- Time = 2 years

\[ \text{Future Population} = 180,000 \times (1 + 0.10)^2 \]

\[ \text{Future Population} = 180,000 \times 1.1^2 \]

\[ \text{Future Population} = 180,000 \times 1.21 \]

\[ \text{Future Population} = 217,800 \]

Therefore, the population after 2 years will be 217,800. Hence, the correct answer is 217,800.

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Question 125

Present population of a village is 67600. It has been increasing annually at the rate of 4%. What was the population of the village two years ago ?

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To find the population of the village two years ago, we need to apply a reverse percentage calculation.

Let \( P \) be the population two years ago.

The present population is given as 67,600, and it has been increasing annually at the rate of 4%. This implies that the population two years ago increased by 4% each year for two years.

The formula for reverse percentage change is given by:

\[ P = \dfrac{\text{Present Value}}{(1 + \text{Rate of Change})^{\text{Number of Years}}} \]

Substitute the given values:

\[ P = \dfrac{67,600}{(1 + 0.04)^2} \]

\[ P = \dfrac{67,600}{1.0816} \]

\[ P \approx 62,500 \]

Therefore, the population of the village two years ago was approximately 62,500. Hence, the correct answer is 62,500.

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Question 126

In a city, 40% of the people are illiterate and 60% are poor. Among the rich, 10% are illiterate. The percentage of the illiterate poor population is ?

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Let's denote the following:

- \( I \): the percentage of illiterate people in the city.
- \( P \): the percentage of poor people in the city.
- \( R \): the percentage of rich people in the city.

Given information:
1. \( I = 40\% \) (illiterate people in the city).
2. \( P = 60\% \) (poor people in the city).
3. Among the rich (\( R = 100\% - P = 40\% \)), \( 10\% \) are illiterate.

We need to find the percentage of the illiterate poor population.

The percentage of illiterate poor people (\( I \cap P \)) can be found using the formula:\[ I \cap P = I - (R \cap I) \]

We know that \( R \cap I \) is the percentage of rich illiterate people, which is \( 10\% \) of \( R \).

\[ R \cap I = 10\% \times R = 10\% \times 40\% = 4\% \]

Now, substitute the values into the formula:

\[ I \cap P = I - (R \cap I) \]

\[ I \cap P = 40\% - 4\% = 36\% \]

Therefore, the percentage of the illiterate poor population is \( 36\% \). Hence, the correct answer is 36.

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Question 127

In a factory, the production of cycles rose to 48, 400 from 40,000 in 2 years. The rate of growth per annum is ?

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To find the rate of growth per annum, you can use the formula for compound annual growth rate (CAGR):

\[ CAGR = \left( \dfrac{\text{Ending Value}}{\text{Beginning Value}} \right)^{\dfrac{1}{\text{Number of Years}}} - 1 \]

In this case:
- Beginning Value (BV) is 40,000,
- Ending Value (EV) is 48,400, and
- Number of Years is 2.

Substitute these values into the formula:

\[ CAGR = \left( \dfrac{48,400}{40,000} \right)^{\dfrac{1}{2}} - 1 \]

\[ CAGR = \left( 1.21 \right)^{\dfrac{1}{2}} - 1 \]

\[ CAGR = 0.1 \]

Convert this to a percentage:

\[ CAGR = 10\% \]

Therefore, the rate of growth per annum is 10%. Hence, the correct answer is 10%.

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Question 128

The population of a village increases by 5% annually. If its present population is 4410, then its population 2 years ago was ?

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Let's denote the present population of the village as \( P \).

According to the given information, the population increases by 5% annually. Therefore, the population after one year (\( P_1 \)) is given by:\[ P_1 = P + 0.05P = 1.05P \]

After the second year, the population (\( P_2 \)) becomes:\[ P_2 = 1.05P + 0.05(1.05P) = 1.1025P \]

Given that the present population is \( 4410 \), we can set up the equation:\[ 1.1025P = 4410 \]

Now, solve for \( P \):\[ P = \dfrac{4410}{1.1025} \]

\[ P \approx 4000 \]

Therefore, the population 2 years ago was approximately \( 4000 \). Hence, the correct answer is 4000.

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