Question

Jassi inherited Rs 12000.she invested part of it at 10% and the rest of at 12% p.a. simple interest .her annual income from these investment is Rs 1280 . How much did she invest at each rate.

Answer 1

She invested Rs 11200 at the rate of 10% and Rs 800 at the rate of  20%.

Step-by-step explanation:

We use the formula as;

• SI = $\dfrac{principal \times rate \times Time}{100}$

• Now, Jassi has total Rs 12000.

• Suppose, she invested Rs x from it at the rate of 10% for one year of SI.

• And, she invested rest of the amount as Rs (12000 - x) at the rate of 12% for 12% of SI.

Now, if she invested Rs x at the rate of 10% for one year. Then,

• $SI_1 = \dfrac{x \times 10 \times 1}{100}$

Similarly, if she invested Rs (12000-x) at the rate of 12% for one year. Then,

• $SI_2 = \dfrac{(12000-x) \times 12 \times 1}{100}$

Here, we are given that she earned total Rs 1280 through SI.

It means that,

• $SI_1 + SI_2 = 1280$

$\dfrac{x \times 10 \times 1}{100} + \dfrac{(12000-x) \times 12 \times 1}{100} = 1280$

By solving it , we get as,

1280 = $\dfrac{x}{10} + \dfrac{2(12000-x)}{10}$

x = Rs 11200 And  (12000 - x) = Rs 800

Thus, she invested Rs 800 at the rate of 12% and Rs 11200 at the rate of  10%.

Answer 2

Step-by-step explanation:

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