Total number of cases = 10c4
Favorable number of cases = 4c2. 6c2
{Since, we are to select 2 children out of 4 and remaining 2 persons are to be selected from remaining 6 persons ( 2W + 4M)}
? required Probability = 4c2 . 6c2 / 10c4
= [{(4 x 3) / (2 x 1)} x {(6 x 5) / (2 x 1)}] / [ (10 x 9 x 8 x 7) / (4 x 3 x 2 x 1)]
= [(12/2) x (30/2)] / 210
= 90 / 210
= 9 /12
Suppose they meet after y hours .
Then, 21y - 16y = 60
? y = 12
?required distance = (16 x 12 + 21 x 12) km.
= 444 km.
Let Reena?s present age be 'K' yrs.
Given:{(K+3) x 4} - {(K-3) x 3)}
=> K = 21 yrs
So her present age is 21 yrs.
Then, her age after 1 year is 22 yrs.
Let C's age be x years.
Then, B's age = 2x years.
A's age = (2x + 2) years.
(2x + 2) + 2x + x = 27
5x = 25 => x = 5
Hence, B's age = 2x = 10 years.
suppose the ages of Sunil and Anil are 8x yr and 7x yr, respectively.
After 6 yr, = 136x + 102 = 133x + 114
136x ? 133x = 114 ? 102
3x = 12 X = 12/3 = 4
Age of Sunil = 8x = 8 × 4 = 32 yr
Present age Anil = 7x = 7 × 4 = 28 yr
Required difference = (32 ? 28) = 4 yr
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