Question

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∆∆∆∆∆GOOD MORNING∆∆∆∆∆
••••100 MARKS = 3 EASY QUESTION.••••
PLEASE ANSWER CORRECTLY.
SO LET'S SEE THE EASY QUESTION.

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(1). IN HOW MANY YEARS WILL A SUM OF MONEY TRIPLE ITSELF AT 10 PERCENT PER ANNUM.

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(2). A SUM OF MONEY AMOUNTS TO RS 7502 IN 2 YEARS AND TO RS 9680 IN 5 YEARS AT SI. FIND THE SUM AND THE RATE PERCENT.

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(3) THE COST OF 6 PENCILS IS EQUAL TO THE SELLING PRICE OF 5 PENCIL . FIND THE PROFIT PERCENT.

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Answer 1

HEY MATE......✌
HERE IS YOUR ANSWER....... ✌
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===========================
1.
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let the principal be x

then amount be 3x

Rate of interest: 10% /p.a.

let time be "t" years

S.I. = $\frac{p \times r \times t}{100}$

=> $\frac{x \times 10 \times t}{100} = \frac{xt}{10}$

=>according to the question,

$x + \frac{xt}{10} = 3x \\ = > \frac{10x + xt}{10} = 3x \\ = > x(10 + t) = 30x \\ = > 10+ t = 30 \\ = > t = 20$

HENCE,

➡time = 20 years.✔✔

(^_^)

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2.

Let the sum of money be x

case i:

time = 2 years

amount = 7502

let rate= r%

S.I. = PxRxT/100

=>S.I. = $\frac{2xr}{100}$

=> amount:

$\frac{2xr}{100} + x \\ = \frac{2xr + 100x}{100}$ = 7502

=>2xr + 100x = 750200 ----------(1)

Case ii:

time = 5 years

amount: 9680

S.I. = 5xr/100

Amount :

$\frac{5xr + 100x}{100}$ = 9680

=> 5xr + 100x = 968000 ---------(2)

Subtracting (1) from (2), we get:

3xr= 217800

=> xr =rs 72600 -------(3)

by putting the value of xr in equation 2, we get

5 x 72600 + 100x = 96800
=> 100x = 968000 - 363000
=> x = 6050✔✔

hence,
sum of money = rs 6050

by putting the value of x in equation 3, we get:

r = 72600 /6050 = 12

hence,

rate % = 12%✔✔

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3.

Cost price of 6 pencil = selling price of 5 ✏ pencils

Profit = S.P. of 6 pencil - C.P. of 6 pencil

=> Profit = S.P. of 6 pencils - S.P. of 5 pencils [given]

=> profit = S.P. of 1 pencil

let selling price of 1 pencil = rs x

profit % = $\frac{x \times 100}{5 x}$

=> 20 % ✔✔

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$</font></b>$
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PLEASE FOLLOW ME.......✌

BY SHIVAM SHAURYA

Answer 2

(1)

Let the Principal be P.

A = 3 P

A = P + I where I is the Interest

P + I = 3 P

= > I = 2 P

Note that I = PRT/100

Hence PRT/100 = 2 P

= > RT/100 = 2

= > RT = 200

R = 10%

= > 10 T = 200

= > T = 200/10

= > T = 20 years .

The time is twenty years.

(2)

Let the sum be X .

X amounts to 7502 in 2 years .

X + I = 7502

= X + XRT/100 = 7502

= X + 2 XR / 100 = 7502

= X + XR/50 = 7502

= X ( 1 + R/50 ) = 7502 .......( 1 )

X amounts to 9680 in 5 years .

X + XRT/100 = 9680

= X ( 1 + 5R/100 ) = 9680

= X ( 1 + R/20 ) = 9680

= X = 9680 / ( 1 + R/20 )

Put this in 1

9680/( 1 + R/20 ) ( 1 + R/50 ) = 7502

= ( 1 + R/50)/( 1 + R/20 ) = 7502/9680

= ( 50 + R ) / 50 / ( 20 + R ) / 20 = 7502/9680

= ( 100 + 2 R ) / ( 100 + 5 R ) = 7502 / 9680

= 9680 ( 100 + 2 R ) = 7502 ( 100 + 5 R )

= 9680 ( 2 R ) + 968000 = 7502 ( 5 R ) + 750200

= - 19360 R + 37510 R = 217800

= 18150 R = 217800

= R = 217800/18150

O_o

= R = 12

Put this in 1

X ( 1 + 12/50 ) = 7502

= X ( 62/50 ) = 7502

= X = 7502 * 50/62

= X = 121 * 50

= X = 6050

ANSWER:

The sum is 6050 and rate is 12%

3)

Let C.P of one pencil be x .

C.P of 6 pencils = 6 x

6 x = 5 * S.P of one pencil .

S.P of one pencil = 6 x / 5

Profit = 6 x / 5 - x

= x / 5

Profit % = x / 5 / x × 100

= 100/5 %

= 20%

The profit is 20%