TCS Company Numerical Ability LCM and HCF

A B C D all 4 have to cross a bridge. Bt dey can go only in pair. Dey also have to carry a lamp in each travel which z one side of the bridge. How much min tym will 4 of dem require to cross it if the speed of A is 1 min B is 2 min C is 7 min n D is 10 min?

Ans was 17.
Apart from solving cn plz any1 hlp me to find the right approach to the solution? Or does it just follows hit n trial method?

Read Solution (Total 2)

first A and B will travel together to cross the bridge ,so the total time taken will be highest of the two that is 2 min.
now a will come back with the candle it will take 1 min
so until now the total time is 2+1=3 min
now C and D will cross the bridge and the time will be 10 min
total time until now is 10+3=13 min
now b will come back and total time 13+2=15 min
A and b will cross the bridge 15+2=17 min
10 years agoHelpfull: Yes(59) No(2)

alwz sart with best two min people and send them
after wards maxm time taking
and at the end set it such that best people will go ........

as in example

a+b-------2min; A.......> 1min =3min in one trip;
c+d-------10min;B.......>2min = 10+2 min trip i.e 12 min;
now again A+b---------2min; Total trip time : 3+12+2=17 min :)
10 years agoHelpfull: Yes(8) No(0)

TCS Other Question

11 March 2003 is Tuesday which contains 365 days in the year. Then what will be the day on 11 March 2004 which contain 366 days. Mr. Swamy, a Professor of an MBA school Laurels is an expert at creating puzzles. On the induction day for the first year MBA students of the academic year 2012 he asked his students to guess his date of birth in the form(dd-mm-yy), where yy represent the last two digits of the year in which he was born.
He put the following conditions before them.
1) In 2012, his age is more than 46 years but less than 49 years.
2) Three of the digits in his date of birth are consecutive odd numbers.
3) There is exactly one natural number of the form (x2 -1) in his date of birth (where x is a single digit odd number).
4) There is exactly one two digit prime number (taken either as dd or mm or yy) in his date of birth.
Now on the basis of the above information answer the following questions.

4. Which is the month in which Mr. Swamy was born?
1] November 2] July 3] August 4] Cannot be determined

5. What is the sum of (d + d + m + m + y + y) in his date of birth?
1] 15 2] 18 3] 23 4] 27

6. On which date (dd) was Mr. Swamy born?
1] 21 2] 11 3] 13 4] Cannot be determined