- Rs. 275
- Rs. 475
- Rs. 575
- Rs. 375

Option 4 : Rs. 375

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Group Y 2021 Full Mock Test

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50 Questions
50 Marks
45 Mins

**Given,**

Difference of 3 years CI and SI = 48

Rate of interest = 20%

**Formula:**

SI = Prt/100

A = P (1 + r/100)^{t}

CI = P [(1 + r/100)^{t} – 1]

Difference CI and SI for 3 years = [Pr^{2} (300 + r)]/100^{3}

Where, P = Principal, r = rate of interest,

**Calculation:**

**Detailed method:**

P [(1 + 20/100)^{3} – 1] – (P × 20 × 3)/100 = 48

⇒ P [216/125 – 1] – 3P/5 = 48

⇒ 91P/125 – 3p/5 = 48

⇒ (91P – 75P)/125 = 48

⇒ 16P/125 = 48

⇒ P = 48 × 125/16

⇒ P = 375

∴ The sum is Rs. 375

__Short Trick__:

[P × 20^{2} × (300 + 20)]/(100 × 100 × 100) = 48

⇒ P × 400 × 320 = 48 × 100 × 100 × 100

⇒ P = (48 × 100 × 100 × 100)/(400 × 320)

∴ P = Rs. 375

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