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AFCAT Model Paper 9

Question : 63 of 100

Marks: +1, -0

Solution:

Given:

Ratio of difference between CI and SI for 3 years and 2 years respectively = 25: 8

Formula used:

Difference between CI and SI for 3 years

=\frac{PR^{2}(R+300)}{100^{3}}

Difference between CI and SI for 2 years

=\frac{PR^{2}}{100^{2}}

Calculation:

According to question:

\left[ \frac{PR^{2}(R+300)}{100^{3}} \right] / \left[ \frac{PR^{2}}{100^{2}} \right] = \frac{25}{8}

Solving LHS:

⇒

\left[ \frac{R+300}{100^{3}} \right] \times 100^{2}

⇒

\frac{R+300}{100} = \frac{R}{100} + 3

R\% + 3

Now,

R\% + 3 = \frac{25}{8}

⇒

R\% = \left( \frac{25}{8} \right) - 3 = \frac{1}{8}

∴ Rate of interest $= \frac{1}{3} = 12.5\%$

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