type 6 si with ratios Section-Wise Topic Notes With Detailed Explanation And Example Questions

Answer: (d)

Using Rule 1,

Case-I,

Interest = 5x - 4x = x

$x = {4x × R × T}/100$

T = $25/R$ years

Case-II,

T = $25/R + 3 = ({25 + 3R}/R)$ years

SI = 7 y - 5y = 2y

$2y = {5y × R × (25 + 3R)}/{R × 100}$

40 = 25 + 3R

3R = 40 –25 = 15 %

R = $15/3$ = 5%

Answer: (a)

Using Rule 1,

$\text"Principal"/ \text"Interest" = 10/3$

$\text"Interest"/ \text"Principal" = 3/10$

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

= $3/10 × 100/5$ = 6% per annum

Answer: (b)

Using Rule 1,

Principal : Interest = 25 : 1

Interest : Principal = 1 : 25

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

= $1/25$ × 100 = 4% per annum

Answer: (c)

Using Rule 1,

$\text"Principal"/\text"Amount" = 10/12$

$\text"Amount"/ \text"Principal" = \text"Principal + interest"/ \text"Principal" = 12/10$

1 + $\text"Interest"/ \text"Principal" = 12/10$

$\text"Interest"/ \text"Principal" = 2/10 = 1/5$

Rate = $1/5$ × 100 = 20%

Answer: (c)

Let the sum lent at the rate of interest 5% per annum is x and at the rate of interest 8% per annum is (1550 - x)

According to the question,

${x × 5 × 3}/100 + {(1550 - x) × 8 × 3}/100$ = 300

${15x}/100 + {37200 - 24x}/100$ = 300

15x + 37200 - 24x = 300 × 100

9x = 7200

x = Rs.800 and,

1550 - x = 1550 - 800 = Rs.750

Ratio of money lent at 5% to that at 8%

= 800 : 750 = 16 : 15

Answer: (b)

Using Rule 1,

First part = Rs. x and second part

= (12000 - x )

${x × 3 × 12}/100 = {(12000 - x) × 9 × 16}/200$

$x/{12000 - x} = {9 × 16 × 100}/{3 × 12 × 200}$

= $2/1$ = 2 : 1