Question

At what rate percent per annum will a sum of money double itself in 8 ​

Answer 1

Answer:

At what rate percent per annum will a sum of money double in 8 years.

A) 12.5%

B) 13.5%

C) 11.5%

D) 14.5%

Answer: A) 12.5%

Explanation:

Let principal = P, Then, S.I.= P and Time = 8 years

We know that S.I. = PTR/100

Rate = [(100 x P)/ (P x 8)]% = 12.5% per annum.

Answer 2

$\underline{ \mathfrak{ \: AnswEr:- \: }}$

$\text{\blue{\:\:The required rate of interest = 12.5\%}}$

$\underline{ \mathfrak{ \: Given:- \: }}$

$\text{ \orange{A sum of money become double of itself}} \\ \text{ \orange{ in 8 years under simple interest.}}$

$\underline{ \mathfrak{ \: Need \:\: to \:\: find:-\: }}$

$\text{\red{\:\:The required rate of interest = ?}}$

$\underline{ \mathfrak{ \:Let:- \: }}$

• $\text{ \green{The rate of interest be r.}}$
• $\text{ \red{The time be 8 years.}}$
• $\text{ \green{The principal be Rs. 100. }}$
• $\text{ \red{The amount be Rs. 200.}}$

$\underline{ \mathfrak{ \: \: Formula \: \: used \: \: here:- \: \: }}$

$\sf{ \green {Simple \: \: Interest = Amount - Principal }}$

$\underline{ \mathfrak{ \: Putting\:\:the\:\:values:- \: }}$

$\sf{ \green{\longrightarrow\: Simple\:\: interest = Rs.200 - 100 }}$

$\: \: \: \: \: \: \: \: \: \sf{ \green{\longrightarrow \: Simple\:\: interest = Rs. 100}}$

$\underline{ \mathfrak{ \: \: Again,Formula \: \: used \: \: here:- \: \: }}$

$\: \: \: \: \: \: \: \: \: \: \: \sf{Simple\: Interest = \dfrac{P \times r \times t}{100}}$

$\underline{ \mathfrak{ \: Putting\:\:the\:\:values:- \: }}$

$\sf{ \longrightarrow \:100 = \dfrac{ \cancel{100} \times r \times 8}{ \cancel{100}} }$

$\sf{ \longrightarrow \:100 = r \times 8 }$

$\sf{ \longrightarrow \: Rate\:of\: interest = \dfrac{100}{8} }$

$\sf{\longrightarrow\:Rate\:of\: interest = 12.5\%}$

$\underline{ \mathfrak{ \: \: Therefore:- \: \: }}$

$\sf{\green{The \: \: required\: \: rate \: \: of \: \: interest\: \: is \: \underline{ \: 12.5\% \: }}}$

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