Answers :-
1. (a) Principal = Rs. 2550,
Rate¿ = 4¿ = 26/25 (26 → Installment, 25 →
Principal)
Time = 25× 26 : 26× 26
IInd year 625 : 676
Note: Installment will be same in both cases.
According to the question,
1275 units = Rs. 2550
1 unit = Rs. 2550/1275
676 units = Rs. 2550/1275 × 676
Rs. 1352
2.(d)
3. (d) 540 = P × R × 3/100
PR = = 18000 …………… (i)
CI = P [(1 + R/100)2 – 1]
376.20 = P [(1 + R/100)2 – 1]
= P [R2/(100)2 + 2PR/100]
= 18000 × R/(100)2 + 2× (18000/100)
= 376.20 = 18 × R/10 + 360
= 376.20 – 360 = 18R/10
R = 162/18 = 9%
From (i) P × R = 18000
P × 9 = 18000
P = Rs. 2000
4. (a) Rate 8 % = 35/4% = 7/80 = 2/25
5. (d) Amount after three years = Rs. 2662
Amount after two years = Rs. 2420
→ Net interest earned in the 3rd. = 2662 – 2420 =
Rs. 242
→ Rate of interest (r) = 242/2420× 100 = 10¿
Thus 2nd year’s amount is principal for 3rd year
6. (d) Given Amt. = Rs. 12100
R% = 10% = 1/10
Time = 2 years
Total amount for 2 year
= 10 + 10 + 1 + 10 = 121
→ 121 units → Rs. 12100
→ 1 unit → 100
→ Principal = 100 unit
= 100 × 100 = 10000
7. (d) Compound Interest = Rs. 1361,
Time = 3 years, Rate % = 5 % = 1/20
According to the question,
1261 units = Rs. 11261
1 unit = Rs. 1261/1261 = Rs. 1
8000 units = 8000 × 1 = Rs. 8000
Thus, Hence Required Principal = Rs. 8000
8. (c) Rate% = 4% time = (t1)= 1 year
Amount = Rs. 7803
When interest is compounded half-yearly
New Rate% = 4/2 = 2%
Time = 1 × 2 = 2 years
Required Rate% for 2 years CI
= 2 + 2 + (2 × 2)/100 = 4.04%
According to the question,
(100 + 4.04)% of sum = Rs. 7803
Sum = 7803/104.04 × 100 = Rs. 7500
Alternate:
Time = 2 years,
Rate% = 4/2, 2% = 1/50
According to the question,
2601 units = Rs. 7803/2601 = Rs. 3
2500 units = Rs. 3 × 2500 = 7500 Rs.
Thus, Hence Sum = Rs. 7500
9. (b)
Since Installment is equal hence multiply equation (i)
by 21
→ total principal = 420 + 400 = 820 units
→ 820 units → Rs. 15
→ 441 units → Rs. 6615
→ Each installment
= Rs. 6615
10. (b) Principal = Rs. 21000
Rate = 10¿ = 1/10 = 11/10 (11 → Installment, 10
→ Principal)
