#075:Poison Pill

On week five of the hit Perplex City reality show, 'The Lab', the labmates awakened to a surprise challenge involving five full jars of pills.

Information:

Four of the jars had pills weighing 10g in them, with the remaining jar having 'poisoned' 9g pills. The labmate who could work out which jar contained the 9g pills with just a single weighing, using the least number of pills, was given an extra week to prepare for their vital research presentation (not something to be sniffed at!).

Can you solve the challenge?

All the pills are shaped identically, and you're not allowed to weigh a pill and then keep adding more while still checking the weight. Only one weighing of as few or as many pills as you want, at once - is allowed.