CUET UG 2025 — General Test Arithmetic

The difference between the amounts after 4 years and 3 years gives the interest earned in the 4th year:

Interest earned in 4th year $= 5950 - 5100 = 850$=5950−5100=850 rupees

In compound interest, this interest was earned in 1 year on the amount that existed at the start of that year.

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The amount at the start of the 4th year was ₹5100 (the amount after 3 years).

So ₹5100 became ₹5950 in 1 year.

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For 1 year, the rate can be calculated as:

Rate $= \dfrac{\text{Interest} \times 100}{\text{Principal} \times \text{Time}}$=Principal×TimeInterest×100​

Rate $= \dfrac{850 \times 100}{5100 \times 1}$=5100×1850×100​

Rate $= \dfrac{85000}{5100}$=510085000​

Rate $= \dfrac{850}{51}$=51850​

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Dividing both numerator and denominator by 17:

$$\dfrac{850}{51} = \dfrac{50}{3}$$51850​=350​

Therefore, the rate of interest per annum is $\dfrac{50}{3}$350​ %.