type 2 increase or decrease in interest rate Section-Wise Topic Notes With Detailed Explanation And Example Questions

Answer: (c)

If the sum lent be Rs. x, then

${x × 2.5 × 3}/100 = 540$

$x = {540 × 100}/{2.5 × 3}$ = Rs.7200

Using Rule 13,

$P_1 = P, R_1 = R, T_1$ = 3

$P_2 = P, R_2 = R + 2.5%, T_2$ = 3

S.I. = Rs.540

540 = ${P × (R + 2.5%) × 3 - P × R × 3}/100$

54000 = 7.5P

P = $540000/75$

P = Rs.7200

Answer: (b)

Using Rule 1,

S.I. = 2352 - 2100 = Rs.252

Rate = ${\text"S.I." × 100}/\text" Principal × Time"$

= ${252 × 100}/{2100 × 2}$ = 6% per annum

New rate = 5%

S.I. = ${252 × 5}/6$ = Rs.210

Answer: (c)

Using Rule 1,

S.I. = Rs.(920 - 800) = Rs.120

Rate = ${\text"S.I." × 100}/\text" Principal × Time"$

= ${120 × 100}/{800 × 3}$ = 5% per annum

New rate = 8% per annum

S.I. = ${800 × 3 × 8}/100$ = Rs.192

Amount = (800 + 192) = Rs.992

Answer: (b)

Using Rule 1,

Let his capital be x.

According to the question,

${x × 11.5}/100 - {x × 10}/100$ = 55.50

or (11.5 - 10)x = 5550

or 1.5x = 5550

or $x = 5550/{1.5}$ = Rs.3700

Answer: (c)

Using Rule 1,

Amount deposited in bank = Rs.x (let)

Difference of rates

= 5 - $7/2 = 3/2%$ per annum

S.I. = ${\text"Principal × Time × Rate"/100$

${x × 1 × 3}/{100 × 2}$ = 105

$x = {105 × 200}/3$ = Rs.7000

Answer: (d)

Interest = Rs.(480–400) = Rs.80

80 = ${400 × r × 4}/100$ ⇒ r = 5

Now, r = 7% (2% increase)

S.I. = ${400 × 7 × 4}/100$ = 112

Amount = Rs.(400+112) = Rs.512