Question

any moderator can solve this

Answer 1

let the principal be ' x '

rate of interest = 10 % per annum

according to question,

amount = 1.5 times of principal
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amount = 1.5 × x = 1.5 x

since , we know that

solve for 't' :
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amount = p [ 1 + ( rt / 100 ) ]

1.5x = x [ 1 + ( 10t / 100 ) ]

1.5x / x = ( 100 + 10t ) / 100

1.5 = ( 100 + 10t ) / 100

15/ 10 = ( 100 + 10t ) /100

( 15 × 100 ) / 10 = 100 + 10t

15 × 10 = 100 + 10t

150 = 100 + 10t

150 - 100 = 10t

10t = 50 => t = 50 ÷ 10 = 5 yrs

therefore,

a certain sum will be 1.5 times the principal in 5 years at the rate of 10 % per annum.

Answer : t = 5yrs

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Answer 2

Let the principal amount be x

Find the interest for 1 years:

1 year = 10% interest

1 year = 0.1x

Find the number of years to reach 0.5x:

1 year = 0.1x

Number of years needed = 0.5x/0.1x = 5 years

Answer: 5 years