सविस्तर स्पष्टीकरण (Detailed Explanation):
अचूक उत्तर: पर्याय (3)
दिलेल्याप्रमाणे:
3 वर्षांसाठी सरळ व्याज = 1200 रुपये
व्याज दर = 5%
वापरलेले सूत्र:
सरळव्याज, SI = (P × R × T) ÷ 100
जिथे
P = मुद्दल रक्कम
R = वार्षिक व्याजदर
T = कालावधी वर्षांमध्ये
चक्रवाढ, CI = P(1 + R/100)n - P
जिथे
P = मुद्दल रक्कम
R = वार्षिक व्याजदर
T = कालावधी वर्षांमध्ये
गणना:
समजा मुद्दल रक्कम P आहे
प्रश्नानुसार
⇒ \({1200\ =\ {P\ \times 5\ \times 3\over 100}}\)
⇒ \({P\ =\ {1200\ \times 100\over 15}}\ =\ 8000\)
प्रश्नानुसार चक्रवाढ व्याज
⇒ \({CI\ =\ 8000\ \times [{(1\ +\ {5\over 100})^3}\ -\ 1]}\)
⇒ \({CI\ =\ 8000\ \times [{(1\ +\ {1\over 20})^3}\ -\ 1]}\)
⇒ \({CI\ =\ 8000\ \times [{( {21\over 20})^3}\ -\ 1]}\)
⇒ \({CI\ =\ 8000\ \times [{( {9261\over 8000})}\ -\ 1]}\)
⇒ \({CI\ =\ 8000\ \times {[9261\ -\ 8000]\over 8000}}\)
⇒ CI = 9261 - 8000
⇒ CI = 1261
चक्रवाढ व्याज = 1261
∴ आवश्यक उत्तर 1261 आहे.
Shortcut Trick
Simple interest for 1 year = 1,200 ÷ 3 = ₹400.
Interest on 1st year interest (5% of 400) = ₹20.
Interest on that interest (5% of 20) = ₹1.
Compound interest (3 years) = 3 × (400) + 3 × (20) + 1 × (1) = 1,200 + 60 + 1 = ₹1,261.
∴ The correct answer is ₹1,261.
Alternate Method
Given: Simple Interest (SI) = ₹1,200, Rate (R) = 5% p.a., Time (T) = 3 years.
Formula Used: SI = (P × R × T) ÷ 100; CI = P[(1 + R/100)^(T) − 1]
⇒ 1,200 = (P × 5 × 3) ÷ 100
⇒ 1,200 = 15P ÷ 100
⇒ P = (1,200 × 100) ÷ 15 = ₹8,000
⇒ CI = 8,000[(1 + 5/100)^(3) − 1]
⇒ CI = 8,000[(21/20)^(3) − 1]
⇒ CI = 8,000[9,261/8,000 − 1]
⇒ CI = 8,000 × (1,261/8,000) = ₹1,261.
∴ The correct answer is ₹1,261.
Related Concepts:
Difference between CI and SI for 2 years
The difference is given by the formula: D = PR^(2) ÷ 100^(2).
Difference between CI and SI for 3 years
The difference is given by the formula: D = [PR^(2)(300 + R)] ÷ 100^(3).
Effective Rate of CI
For a rate of r% for 3 years, the effective rate is [3r + 3r^(2)/100 + r^(3)/10000]%. For 5%, it is 15.7625%.
स्पष्टीकरण आकृती (Solution Visual Diagram):
Solution Diagram