Quantitative Aptitude - Arithmetic Ability Questions

From the given data in the question,

$$\begin{gathered} 279841 = 160000 x 1+15100t \\ 279841160000 = 115100t \end{gathered}$$

t = 4 years.

A man's average monthly expenditure for the first four months of the year = Rs.231.25.
For four month = 231.25 * 4 = Rs. 925
For next five month he spend = 231.25 + 22.75 for one month.
In five month he spend = (231.25 + 22.75) X 5 = 1270
If the person spent Rs. 605 in all during the remaining three months of the year,
Total expense = 925+1270+605= 2800
Saving = 3500-2800 = 700
% saving = 700/3500 * 100 = 20%

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.

Ans. 
Distance covered by 1st train in 4 hours = 80*4 = 320 km
Relative speed of 2nd train = 120-80 = 40 km
It will overtake another train in 320/40 = 8 hours
Distance between overtake point and station A = 8*120 = 960 km

Cost of Rs. 100 stock   = Rs. (100-15)

Cost of Rs. 6400 stock = Rs.85100*6400 = Rs. 5440.

ATQ,

P : Q = 5 : 12 = 10 : 24

Q : R = 4 : 5.5 = 24 : 33

P:Q:R = 10 : 24 : 33

Sum of the ratios = 10 + 24 + 33 = 67

Difference between the share of R & Q

= (33-24/67 x 2018)

= 9/67 x 2018

= Rs. 271.

Let the number of girls = x

=> x + x + 4 = 12

=> 2x = 8

=> x = 4

=> Number of girls = 4

=> Number of boys = 4 + 4 = 8