Quantitative Aptitude - Arithmetic Ability Questions

Total student= 39, boys : girls = 2:1, hence no of boys= 2/3(39)= 26
num of girls= 1/3(39) = 13 , since radhika ranked 15 among 39 student from top
and ranked 8 among girls from bottom , this means 7 girls are below radhika, rest 13-9= 5 girls are above her, now from 14 toper 5 are girls hence 14-5=9 boys.
Hence num of boys below radhika are 26-9=17

Last digit for the power of 6 is 6 (always)

Power cycle of 7 is 7, 9, 3, 1.

Now 467/4 gives a remainder of 3

Then the last digit is 73 = 3

Last digit is 6 + 3 = 9.

Here clock-wise and anti-clockwise arrangements are same.

Hence total number of circular–permutations: 18P122*12 = 18!6*24

Let the number is = x

(89)² + x² = 16202

x² = 8281

x = 91

=> (1/26) of 91 = 3.5

For ticking 6 times, there are 5 intervals.

Each interval has time duration of 30/5 = 6 secs

At 12 o'clock, there are 11 intervals,
so total time for 11 intervals = 11 x 6 = 66 secs.

Part filled by (A + B) in 1 minute = (1/60 + 1/40) = 1/24
Suppose the tank is filled in x minutes.
Then, x/2(1/24 + 1/40) = 1
(x/2) * (1/15) = 1 => x = 30 min.

On dividing we get

75)8485(113
     75
     ------
       98
       75
      ------
       235
       225
      ------
         10
      ------
Required number = (8485-10)=8475.