CAT Questions

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Any person can have only 1 birthday i.e, the day he was born. And every year we celebrate it's anniversaries.

The ratio of X and Y ages at present is 4:5. 

Then, the ratio 20 years ago will not be more than the ratio at present.

So, from the options 9:10 is not satifying => its ratio is 0.9 which is greater than presnt ratio of 0.8.

Let the speed of the stream = x kmph

From the given data,

 129+x+129-x=3 hrs

3x2 = 27

=> x = 3 kmph

Therefore, the speed of the stream = 3 kmph

let 't' be the time after which they met since L starts.

Given K is 50% faster than L

50 t + 1.5*50(t-1) = 300

50 t +75 t = 300 + 75

t = 375 / 125 = 3 hrs past the time that L starts

So they meet at (9 + 3)hrs = 12:00 noon.

An Indian boy has won the world’s largest pre-college science competition in the US in the environmental engineering category for his project on biodegradation of pesticides. Prashant Ranganathan, a 12th grader from Jamshedpur, alongwith over 20 high school students from various parts of India, participated in the Intel International Science and Engineering Fair.

The total number of ways of forming the group of ten representatives is ²²C₁₀.
The total number of ways of forming the group that consists of no seniors is ¹⁰C₁₀ = 1 way
The required number of ways = ²²C₁₀ - 1

Except pineapple remaining all three are types of apples.

Pineapple is what kind of apple isn't an apple.

According to Pradeep : 20,21 or 22...(1)
According to his brother : not 22....(2)
From (1)&(2), the birthday falls on February 20 or 21.