Question: In a room there's 100 people, 99% are left handed. How many left handed people need to leave to bring it to 98%?
The question is not so simple; and “1” is definitely NOT the right answer. Do share your responses quickly and tell us how you did it.
Bonus tips for doing it mentally!
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@ramani-VR4O43 • Dec 16, 2024
50 lefties have to leave. The lone right hander should not leave. That leaves 1 RH and 49 LH. That gives (49 LH/ 50 total)x 100 = 98% LH
@thebigk • Dec 16, 2024
Fantastic!
@cKhpITB • Dec 19, 2024
Let's break this down step by step.
We need to bring the percentage of left-handed people down to 98%. This means that the number of left-handed people needs to be 98% of the new total number of people in the room.
Let ( x ) represent the number of people who need to leave the room. After ( x ) people leave, there will be ( 100 - x ) people remaining in the room.
We know that, since no right-handed people are leaving, the number of left-handed people will still be 99, so we want:
[ \frac{99}{100 - x} = 0.98 ]
Now, solve for ( x ):
[ 99 = 0.98(100 - x) ]
[ 99 = 98 - 0.98x ]
[ 99 - 98 = -0.98x ]
[ 1 = -0.98x ]
[ x = \frac{1}{0.98} \approx 1.02 ]
Since the number of people must be a whole number, round up to ( x = 2 ).
Thus, 2 people need to leave the room to bring the percentage of left-handed people down to 98%.
@cKhpITB • Dec 19, 2024
ChatGPT say’s this
@thebigk • Dec 20, 2024
Haha - ChatGPT is useless when it comes to solving problems with logic. The correct answer is 50.
@72TFFzJ • Dec 21, 2024
Let, x will be the person So remaining total person after removing = 100-x Remaining left handed person in room after removing=99-x Remaining left handed person in room = 98% (given in question) 99-x/100-x = 98/100 By solving above eqn we get x = 50 that is the answer.
@ApJy8xU • Dec 24, 2024
New guy here ... Another non-algebraic way of looking at this (solve mentally is:
99% of 100 people are LH means 99 are LH and 1 RH
We are only removing LH people, so the fraction of LH over total will always be (N-1)/N, i.e. the numerator will always be 1 less then the denominator
So we need a fraction where (N-1)/N = 0./98
Looking at the target of 98%, this is 98/100 (difference of 2)
Reducing this (divide top and bottom by 2), gives 49/50 which is a difference of 1
Initial LH was 99, target is 49, so 50 LH must leave the room.
so wha
@thebigk • Jan 7, 2025
If you really think 'hard', you can visualise that:
At 99% left-handed population, the room composition is: 100 people: 1 RH, 99LH At 98% left-handed population, the room composition is 50 people: 1 RH, 49 LH
Basically, it takes time to 'understand' that 1 RH person is now representing the 2% of the population; for which we need to take out 50 LH people.
Don't know how to simplify this further.
@OSeFZ8o • Jan 23, 2025
If i had to mislead people for money, this is the formula i will definetly use...
