type 5 si on ‘n’ years & ‘x/y ‘of sum Practice Questions Answers Test with Solutions & More Shortcuts

Answer: (a)

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

1200 + ${1200 × 7 × r}/{12 × 100}$

= Amount (A)

1200 + 7r = A ...(i)

and, 1016 + ${1016 × 5 × r}/{2 × 100}$ = A

1016 + 25.4r = A ...(ii)

1016 + 25.4r = 1200 + 7r

25.4r - 7r = 1200 - 1016

18.4r = 184 ⇒ r = $184/{18.4}$

= 10% per annum

Answer: (a)

$\text"Interest"/ \text"Principal" = 3/8$

Rate = ${\text"SI" × 100}/\text"Principal × Time"$

= $3/8 × 100/{25/4}$

= $3/8 × 400/25$ = 6% per annum

Using Rule 5,

Here, n = $3/8$, T = $25/4$ years.

R = ${n × 100}/T$

= $3/8 × 100/{25/4}$ ⇒ R = 6%

Answer: (b)

$\text"Simple interest"/\text"Principal" = 1/4$

Rate = ${\text"SI" × 100}/\text"Principal × Time"$

= ${1 × 100}/{4 × 5} = 5%$ per annum

Using Rule 5,

Here, n = $1/4$, T = 5 years

R = ${n × 100}/T$

= $1/4 × 100/5$ = R = 5%

Answer: (c)

Rate = ${\text"SI" × 100}/\text"Principal × Time"$

= $12/25 × 100/4$ = 12% per annum

Using Rule 5,

Here, n = $12/25$, T = 4 years.

R = ${n × 100}/T$

R = $12/25 × 100/4$

R = 12%

Answer: (a)

P = $\text"100 × SI"/\text"R × T"$

= $\text"100 × x"/\text"x × x"$ = $100/x$