Question

find the time is rupees 8000 lent at CI at 20% amount rupees 8820 the interest being compound quarterly.​

Answer 1

Answer:

Step-by-step explanation:

Interest is being compound quarterly

hence    r =  20%/4

                =  5%

We know,

Sum = Principal ( 1 +  r/100 )^n

8820 = 8000( 1 + 5/100 )^n

8820/8000 = (21/20)^n

441/400 = (21/20)^n

(21/20)^2 = (21/20)^n

n = 2

Since interest compound quarterly so n = 2×4

                                                                      = 8

Answer 2

The time is two years.

Step-by-step explanation:

Since we have given that

Principal = Rs. 8000

Amount = Rs. 8820

Rate of interest = 20% compound quarterly

So, it becomes,

$A=P(1+\dfrac{r}{400})^{4n}\\\\8820=8000(1+\dfrac{20}{400})^{4n}\\\\\dfrac{8820}{8000}=(1+\dfrac{20}{400})^{4n}\\\\1.1025=(1+\dfrac{1}{20})^{4n}\\\\1.1025=\dfrac{21}{20}^{4n}\\\\1.1025=1.05^{4n}\\\\1.05^2=1.05^{4n}\\\\4n=2$

So, the time is two years.

# learn more:

In what time will Rs 8000 at 5% per annum compounded annually will amount to rupees 8820

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