Question

At what rate percent per annum will ₹400 yield an interest of ₹78 in 1 1/2 years

Answer 1

HERE IS YOUR ANSWER FRIEND.
here,
P = 400
T = 11/2
S.I. = 78
Applying formula of SI
78 = (400×R×11)/(100×2)
78 = 22 R
R = 78/22
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R = 3.54%
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HOPE YOU GOT HELP FROM MY ANSWER.

Answer 2

hye

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rate of interst = r%

we have to find At what rate percent per annum will ₹400 yield an interest of ₹78 in 1 1/2 years

simple interst = 78

principal = 400

so the amount will be => s.i + p

                                   => 400+78
             
                                         =>478

time = $1\frac{1}{2}$

           = $\frac{(2*1 )+1}{2}$

        =    $\frac{3}{2}$

rate of interst = $\frac{100 * s.i }{p*t}$

                       =>$\frac{100*78*2}{400*3}$

                        =>13%

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hope it helps