CUET UG 2025 — General Test Arithmetic

For money to double, the amount becomes 2 times the principal.

If the principal is $P$P, the final amount is $2P$2P.

The simple interest earned is:

$$SI = 2P - P$$SI=2P−P

$$SI = P$$SI=P

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The simple interest formula is:

$$SI = \dfrac{P \times R \times T}{100}$$SI=100P×R×T​

Where $P$P is the principal, $R = 12.5\%$R=12.5% per annum, and $T$T is the time in years.

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Since the simple interest equals the principal:

$$P = \dfrac{P \times 12.5 \times T}{100}$$P=100P×12.5×T​

Dividing both sides by $P$P:

$$1 = \dfrac{12.5 \times T}{100}$$1=10012.5×T​

$$100 = 12.5 \times T$$100=12.5×T

$$T = \dfrac{100}{12.5}$$T=12.5100​

$$T = \dfrac{100}{\frac{25}{2}}$$T=225​100​

$$T = 100 \times \dfrac{2}{25}$$T=100×252​

$$T = \dfrac{200}{25}$$T=25200​

$$T = 8$$T=8

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Therefore, the sum of money will double itself in 8 years.