More probability
9 pieces of paper are put in a box, each piece of paper containing a number on its face, each piece labelled with numbers from 1 to 9. If I were to draw three out at random, what is the probability of the combination of numbers being in arithmetic progression?
Write your answer as a percentage to 3 decimal places. For example, 50% will be written as 50 in the answer box.
The answer is 19.048.
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
1 solution
@Krishna Karthik
I am planning to give you some questions of mechanics here.
Did u have studied Rotational mechanics.?
Log in to reply
I can learn rotational mechanicals; not too hard. I know some basics.
Log in to reply
@Krishna Karthik
Here are some problems
All problems are taken from Pathfinder a famous good physics book for JEE preparation
Solving using paper and pen.
@Krishna Karthik
I have given you
2
4
problems.
Give
5
minutes to every problem and solve all question in
2
hours. .
It will increase your problem solving capacity.
Here are some steps.
1)
Take 20-30 white papers.
2)
Take printout of these 24 questions.
3)
set Timer of 2 hours in your watch.
4)
Sit with bottle to be hydrated 2 hours.
5)
Start the test.
Let's see how much you score.
Log in to reply
Got it. lol i'm gonna fail sooooooo hard
Log in to reply
@Krishna Karthik
I have done this with me,
I will share my score only if you will do this and share your score. .
Consider every problems of 1 marks. Test is of 24 marks.
Log in to reply
@Talulah Riley – Ok. I will do it tomorrow.
Log in to reply
@Krishna Karthik – @Krishna Karthik But use pen and paper only bro.
Log in to reply
@Talulah Riley – Of course bro
Log in to reply
@Krishna Karthik
–
@Krishna Karthik
by the way if we give this to Steven sir.
He will crash the whole paper using python within half an hour. Ha ha ha
Log in to reply
@Talulah Riley – Lmao. Engineers, engineers. Oh my gawwd...
Log in to reply
@Krishna Karthik – @Krishna Karthik If we restrict him to use python. He will solve question using python with gunpoint on our head simultaneously.
Bro how do you even get to the level when u only need 5 minutes per question? How can JEE expect such things from 17 year olds?
Log in to reply
@Krishna Karthik i didn't understand what you want to say bro? Please elaborate
Log in to reply
@Talulah Riley – I just said that it's ridiculously hard for 17 year olds; I was just wondering how 17 year olds will be able to do all 24 questions in 2 hours. It's super hard. I probably take 10 minutes-20 for just one question lmao.
Log in to reply
@Krishna Karthik
–
@Krishna Karthik
Practice makes man perfect.
I scored
2
4
1
6
Which is I think very bad score it should be about
f
r
a
c
2
0
2
4
And who said you ,that you have to do all question, you have to solve maximum question as much as you can .
Log in to reply
@Talulah Riley – True. Well, I think 16/24 is personally quite damn good.
If I'm gonna be honest, I'll probably get 10 at maximum lol
Log in to reply
@Krishna Karthik
–
@Krishna Karthik
what do you mean by maximum. Did you have tested it to 2 hours.
It should be a proper integer, it will not like maximum or minimum.
Log in to reply
@Talulah Riley – Yeah, ik. I haven't attempted the test yet.
Log in to reply
@Krishna Karthik
–
@Krishna Karthik
This test was taken by my physics sir in class.
Do you know 20 was the highest score. 17 was the second highest. My rank was 3rd in class.
After the test I got know that this questions are taken from Pathfinder book.
Log in to reply
@Talulah Riley – Which class? IIT coaching? Btw third rank is epic as hell.
Log in to reply
@Krishna Karthik
–
@Krishna Karthik
Last year when I was 16.In FIITJEE coaching.
Many students in the class score 0 , 1 and 2 .
So you should feel proud that you are 2 year small from those guys and you scored about.
Log in to reply
@Talulah Riley – Yeah; I guess so. I think I am probably better at physics than most people in your class. My specialisation is mostly math and stuff.
Log in to reply
@Krishna Karthik
–
@Krishna Karthik
By the way studying in Fiitjee is very expensive.
They give discount in their price according to students intelligence.
But the total fees is around 13k Australia dollar for 2 years.
What do you is it costly for you??
Log in to reply
@Talulah Riley – I don't pay anything. I used resources from the internet to teach myself maths. Sometimes my dad teaches me.
Btw I would rather spend 13k on a grand piano.
Log in to reply
@Krishna Karthik – @Krishna Karthik I was just saying that if you want to take coaching for JEE in Fiitjee then the cost will be that much which is very expensive.
Log in to reply
@Talulah Riley – True. I do find it quite expensive.
Well, I suppose it all comes down to practice.
@Krishna Karthik
I have answer also. Give me your answer . Let me check. And in case any doubt post in Discussion section.
I will definitely help you.
Log in to reply
I am definitely not ready for the test yet.
I won't time myself; I will just casually go through all the questions, if I have doubts, I will post up a discussion. Thanks man :)
@Lil Doug Bro look up some stock images yourself. I'm sure you'll find some.
Log in to reply
@Krishna Karthik so i have right to upload them?
Log in to reply
Stock images are licensed. Yes, you do.
Log in to reply
@Krishna Karthik – @Krishna Karthik I don't have license. If I upload them, afer that I will be in a very big problem
Log in to reply
@Talulah Riley – No. They're available to the public. You don't need a license. They are licensed to everybody .
@Krishna Karthik I think I have to buy image to upload right?
Log in to reply
No no no... you can use stock photos for your own purposes. That's what stock is for. No buying, no licensing. It's free to use for the internet.
Log in to reply
@Krishna Karthik
ok I wil not upload the image right now.
Whenever my name will be changed, then i will upload them. Bye.
the probability is the number of favourable outcomes divided by the total number of outcomes.
The favourable outcomes (the numbers are in arithmetic progression) can be counted.
When we count them, we start to notice a pattern: when the step (increment of arithmetic progression) increases, the number of arithmetic progressions possible in that step decreases by 2.
Therefore, the number of favourable outcomes is:
7 + 5 + 3 + 1
This sum is given by n 2 . The sum is 4 2 = 1 6
the total number of outcomes is the amount of ways which you can select 3 from 9, which is 9 C 3 . This can be found by:
3 ! ∗ 6 ! 9 !
= 3 ! 9 ∗ 8 ∗ 7 = 3 ∗ 4 ∗ 7
therefore the probability is:
3 ∗ 4 ∗ 7 1 6
which in percentage form is 19.048%