@rayus but how come we are getting diffrent answers..i think it should be constant..if ravi can tell us the key that would remove some ambiguity
@cadmium
Should be 50m..
Let L m be the length of the Train, and x m/sec be its speed..
Thus, L/(x- 5/9)= 9,or, L = 9x - 5...(i)[Since 2km/hr = 5/9 m/sec]
Again, L/(x - 10/9) = 10, or, L = 10x - 100/9...(ii)[Since 4 km/hr = 10/9 m/sec]
Solving (i) n (ii), we have L= 50m..n x = 55/9 m/sec..
@ravi.theja said:Find the remainder when the sum 2^100+2^200+2^300..+...+..2^10000 is divided by 7a) 2b) 0c) 1d) 6 e) None of these.
2^100/7 = 2
2^200/7 = 4
2^300/7 = 1
2^400/7 = 2
So the remainder occurs in this pattern 2,4,1,2,4,1...
There are 100 terms
So 33,33,33...The 100th term will again have a remainder 2
So overall remainder = 34*2 +33*4+33*1 mod 7 = 233/7 = 2
@nirzone said:@rayus but how come we are getting diffrent answers..i think it should be constant..if ravi can tell us the key that would remove some ambiguity
for wich question bhai..remainder wala ans is 2 :)
@Logrhythm said:Is it 50 metres?? Let the length of the traing be l and it's speed be v mps=> l/(v - 5/9) = 9and l/(v - 10/9) = 10therefore, l = 9v - 5and l = 10/9*(9v - 10)Solve both equations, l comes out to be 50 metres
Yes it is 50 metres.
@ravi.theja You missed (15,9). Actually no need to calculate exact number x^n-y^n=k has solutions iff k is odd number or multiple of 2n.
Here x^2-y^2=144
(x+y)(x-y)=2^4*3^2. To make sure it is divisible by 4 (2n) find no of ways 2^2*3^2 can be written as product of 2 numbers. 3*3= 9 ways. But x=y will be 1 case which cannot be taken. Also, half of remaining have x>y and other half x
@vbhvgupta said:Which of the followinf is not a perfect square100856, 325137, 945729? how to find quickly?
325137. Perfect squares doesn't end with 2,3,7,8 and have digital sum of 1,4,7,9 always.
@nirzone said:@rayus how about this way..2 (100+200+...10000)..now treating 100, 200 to 10000 as an AP sum would be 505000..now 2*505000/7..remainder would be 6..what say!
sry.. i didnt go thru your answer properly in the first go..
check ques carefully.. its 2^100+2^200+...
you have taken 2*100+2*200+...
thats why the answer is different..
@cadmium said:Q.A train overtakes two persons who are walking in the same direction in which the train is going,at the rate of 2kmph and 4kmph and passes them completely in 9 and 10 seconds respectively. The length of the train is?Please share logical aprroach in detail ,please.
Speed = Distance/time
Length of train = l
Speed of train = s
l/s-2 = 9/3600----1
l/s-4 = 10/3600----2
s-2 and s-4 are the Relative speeds when they are travelling in the same direction
Solving 1 and 2, Speed of train = 22 kmph
Length of train = 1/20 km or 50 m
@pirateiim478 said:Both are same!! Try other question in same post.One more question=> How many right angled triangles are there in which 1. One leg is 122. Hypotenuse will be 12
1. 4 such triangles.
2. None ? :roll:
@Estallar12 said:1. 4 such triangles.2. None ?
estallar bhai.. _/\_ .. aap bhi vapas?? cat 2012 ka kya hua?? meri toh hindi movie ki tragedy ho gayi.. with a bad ending.. ;(
@Estallar12 said:1. 4 such triangles.2. None ?
@Estallar12 __/\__ Don't worry you will face same fate as Doc and RTP!! I know you are not but i just wanted to say
A man left between 8 am-9 am and reaches his destination between 2pm-3pm when both hands are at 180 degrees. Find the total journey time ?
@nikemen said:@ravi.theja how did u get 2 for the second one. also could enlighten me upon the approach u followed?
wich question bhai??
@ravi.theja said:Find the remainder when the sum 2^100+2^200+2^300..+...+..2^10000 is divided by 7
a) 2
b) 0
c) 1
d) 6
e) None of these.
Is it 2??
e(7) is 6
100%6 = 4
200%6 = 2
300%6 = 0
and then it repeats...
100k comes 34 times, 200k and 300k repeats 33 times
So we get - (2*34 + 4*33 + 1*33)%7 = 233%7 = 2.
@nikemen said:@ravi.theja how did u get 2 for the case where 12 is the hypotenuse?
bhai..
a^2+b^2=(12^2)
quickly put values from 1 to 11 in a and check if integral b comes out.. you wont find any solution..
Sorry for the offtopic post - But this is Page 666.
*If you know what I mean* 
@rayus said:bhai..a^2+b^2=(12^2)quickly put values from 1 to 11 in a and check if integral b comes out.. you wont find any solution..
ya...dats y for 12 as hypotenuse ..there's no such triangle and the answer is 0 :)
for 12 as a side u ll get 4 such triangles ...
a^2 - b^2 = 144 it is not + :)
for 12 as a side u ll get 4 such triangles ...
a^2 - b^2 = 144 it is not + :)
Bill and Clinton take the square of a certain decimal number and express it in base 5 and 6 respectively. Then Bush comes and he takes the two representations and assuming that the expressions are in base 10, adds the numbers. Which of the following cannot be the value of the unit창€™s digit of the sum obtained?
a. 0
b. 2
c. 8
d. 6
e. 3
@anytomdickandhary Sir. _/\_