Quantitative Aptitude - Arithmetic Ability Questions

$$\begin{gathered} 3 \\ 32 + 3 = 12 \\ 5 \\ 52 + 5 = 30 \end{gathered}$$

Let the required number be 'p'.

From the given data,

p + 12 = 160 x 1/p

=> p + 12 = 160/p

=> p(p + 12) = 160

=> P^2 + 12p - 160 = 0

=> p^2 + 20p - 8p - 160 = 0

=> P(p + 20) - 8(p + 20) = 0

=> (p + 20)(p - 8) = 0

=> p = -20 or p = 8

As, given the number is a natural number, so it can't be negative.

Hence, the required number p = 8.

Out of 9 persons,4 can be choosen in 9C4 ways =126.

Favourable events for given condition = 2C2*7C2= 21.

So,required probability = 21/126 =1/6.

F=BD×TDBD-TD=200×100200-100=200×100100=Rs.200

Let the principal amount be Rs. x
Calculating SI:
SI for 1 year at 12% rate is Rs (12/100)*x. For 3 years it will be Rs (36/100)*x ------ (1)
Calculating CI:
For 1st year, Interest = (12/100)*x
For 2nd year, interest = (12/100)*x + (12/100)*x + (144/10000)*x
For 3rd year, interest = (12/100)*x + (12/100)*x + (12/100)*x + (144/10000)*x + (144/10000)*x + (1728/1000000)*x. ------ (2)
Subtracting equation 2 and 1 and solving further,
312*144*x/1000000 = 112.32
X = Rs 2500.
Alternative way: Using formula for Difference
between CI and SI for 3 years

we can also use the above formula to find the value of P.