Question

CI of certain sum anually in first year and second year are rupees 400 and rupees 420 respectively then rupees % is ?
. 20%
. 10%
. 5%
. none of the above
Answer it fast!!​

Answer 1

10%

Step by Step

$SI= \frac{PRT}{100}$

Hence,

$400 = \frac{PR2}{100}$

$⟹PR=20000⟹P= \frac{20000}{R}$

Also,

$CI = P[(1+ \frac{R}{100} )^{2} - 1]$

$420 = \frac{20000}{R} [(1+ \frac{R}{100} )^{2} - 1]$

Solving this we get R=10%

ALTERNATE:−

CI for 2 years is=420 Rs.

SI for 2 years is=400 Rs.

Difference of CI and SI is 420−400=20 Rs.

If 2 years SI is 400 Rs.,then 1 year SI is =

$\frac{400}{2} = 200$

20 is the what percent of 200.

$= 20 \times ( \frac{100}{200} ) = 10\%$

If 510% is 200 Rs. then 100% of that principal.

$= 200 \times \frac{100}{10} = 2000$

So the principal is 2000 Rs.

Hence,

$R= \frac{SI \times 100}{PT} = \frac{400 \times 100}{2000} = 10\%$

Answer 2

Answer:

10%

Step by Step

SI= \frac{PRT}{100}SI=

100

PRT

Hence,

400 = \frac{PR2}{100}400=

100

PR2

$10%</p><p></p><p>Step by Step</p><p></p><p>SI= \frac{PRT}{100}SI=100PRT</p><p></p><p>Hence,</p><p></p><p>400 = \frac{PR2}{100}400=100PR2</p><p></p><p>⟹PR=20000⟹P= \frac{20000}{R}⟹PR=20000⟹P=R20000</p><p></p><p>Also,</p><p></p><p>CI = P[(1+ \frac{R}{100} )^{2} - 1]CI=P[(1+100R)2−1]</p><p></p><p>420 = \frac{20000}{R} [(1+ \frac{R}{100} )^{2} - 1]420=R20000[(1+100R)2−1]</p><p></p><p>Solving this we get R=10%</p><p></p><p>ALTERNATE:−</p><p></p><p>CI for 2 years is=420 Rs.</p><p></p><p>SI for 2 years is=400 Rs.</p><p></p><p>Difference of CI and SI is 420−400=20 Rs.</p><p></p><p>If 2 years SI is 400 Rs.,then 1 year SI is =</p><p></p><p>\frac{400}{2} = 2002400=200</p><p></p><p>20 is the what percent of 200.</p><p></p><p>= 20 \times ( \frac{100}{200} ) = 10\%=20×(200100)=10%</p><p></p><p>If 510% is 200 Rs. then 100% of that principal.</p><p></p><p>= 200 \times \frac{100}{10} = 2000=200×10100=2000</p><p></p><p>So the principal is 2000 Rs.</p><p></p><p>Hence,</p><p></p><p>R= \frac{SI \times 100}{PT} = \frac{400 \times 100}{2000} = 10\%R=PTSI×100=2000400×100=10%</p><p></p><p>$

⟹PR=20000⟹P= \frac{20000}{R}⟹PR=20000⟹P=

R

20000

Also,

CI = P[(1+ \frac{R}{100} )^{2} - 1]CI=P[(1+

100

R

)

2

−1]

420 = \frac{20000}{R} [(1+ \frac{R}{100} )^{2} - 1]420=

R

20000

[(1+

100

R

)

2

−1]

Solving this we get R=10%

ALTERNATE:−

CI for 2 years is=420 Rs.

SI for 2 years is=400 Rs.

Difference of CI and SI is 420−400=20 Rs.

If 2 years SI is 400 Rs.,then 1 year SI is =

\frac{400}{2} = 200

2

400

=200

20 is the what percent of 200.

= 20 \times ( \frac{100}{200} ) = 10\%=20×(

200

100

)=10%

If 510% is 200 Rs. then 100% of that principal.

= 200 \times \frac{100}{10} = 2000=200×

10

100

=2000

So the principal is 2000 Rs.

Hence,

R= \frac{SI \times 100}{PT} = \frac{400 \times 100}{2000} = 10\%R=

PT

SI×100

=

2000

400×100

=10%