A sum of money invested at 5% per annum simple interest amount to #285.20 after 3 years, How long will it take the same sum to amount to #434.00 at 7.5% per annum simple interest?
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Correct Answer: Option A
Explanation:
P= ?, R= 5% T= 3, I= ?, A= 285.20
I= P×5×3/100 = 0.15P
Therefore, A = P+I
285.20 = P+0.15P
1.15P = 285.20
Divide both side by 1.15
P = 285.20/1.15 = 248
Therefore, A = P+I
434 = 248+I
I = 434-248 = 186
I = PRT/100
186 = 248×7.5×T/100
186 = 1860T/100
Cross multiply
1860T = 18600
T = 10
P= ?, R= 5% T= 3, I= ?, A= 285.20
I= P×5×3/100 = 0.15P
Therefore, A = P+I
285.20 = P+0.15P
1.15P = 285.20
Divide both side by 1.15
P = 285.20/1.15 = 248
Therefore, A = P+I
434 = 248+I
I = 434-248 = 186
I = PRT/100
186 = 248×7.5×T/100
186 = 1860T/100
Cross multiply
1860T = 18600
T = 10