Question

question no.10 and 12

Answer 1

10) Principle=640

Amount=774.40

Time=2yrs

Rate=?


Amount=p(1+r/100)^n


=774.40=640(1+r/100)^2

774.40÷640=(1+r/100)^2

(11/10)^2=(1+r/100)^2


(Both powers are cut)


11/10=1+r/100

11/10-1/1=r/100

1/10=r/100

R=100/10

R=10%. Answer


Therefore rate %=10%.


12) Here is your answer......

Given :-
Principal = Rs.8000
Rate of interest = 5% per annum
Amount = Rs. 9261

Let Time (n) = 'n'

amount = p( 1+ r/100)^n
9261 = 8000(1+5/100)^n
9261/8000= (1+1/20)^n

(21/20)^3= (21/20)^n

then n = 3 years


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