For students upto class 5 (age upto 12)
annar
Posts: 1
Joined: Sat Sep 17, 2016 8:39 am

Hey guys,
I am no maths genius and need help with this itsy bitsy problem. I know I can easily find the solution by adding them one by one but I was wondering if someone can come up with a quicker solution to this problem, some sort of a formula I guess.

This is the problem:

A train will hold 78 passengers. If it starts out empty and picks up one passenger at the first stop, two passengers at the second stop, 3 passengers at the third stop and so on. After how many stops will it be full?

Thanks, appreciate the help

aritra barua
Posts: 50
Joined: Sun Dec 11, 2016 2:01 pm

Well,this simply reduces the problem to the sum of n consecutive positive integers,which follows the equation :n(n+1)=156,simply factoring the expression,we find n=12 and n cannot be -13 as it is a negative integer.This just solves our problem that at the 12th stop,the bus would be full...

Posts: 36
Joined: Sun Jan 28, 2018 11:43 pm

How have you solve the problem? Can someone suggest me?
যদি জীবনের গোড়ায় কষ্ট কর, তবে পরবর্তী জীবনে কম কষ্ট করতে হবে।

samiul_samin
Posts: 150
Joined: Sat Dec 09, 2017 1:32 pm

$1+2+3+4+5+6+7+8+9+10+11+12=78$
$\int^{\infty}_0 e^{-x} dx=1$