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Re: AREA

Taking four pairs of sign for $(x, y)$ and considering magnitude of $x$ vs. that of $y$ in each of the four cases, you would get a square as the bounded region. It should then be a matter of moments to compute the area.
by SMMamun
Wed Nov 01, 2017 7:15 pm
 
Forum: Secondary Level
Topic: AREA
Replies: 1
Views: 58

Re: Double inequality

There is a mistake in the variables of the problem. I've corrected $ x, y, z$ respectively to $ a, b, c $. We observe that $ bc + ca + ab - 2abc $ $ = bc - abc + ca - abc + ab -abc + abc $ $ = bc(1-a) + ca(1-b) + ab(1-c) + abc $ $ = bc(b+c) + ca(c+a) + ab(a+b) + abc \geq 0 $, because $ a, b, c $ eac...
by SMMamun
Tue Aug 22, 2017 10:04 pm
 
Forum: Algebra
Topic: Double inequality
Replies: 3
Views: 246

Re: Probability-?

To make the correct probabilistic comparison, you'd need to know child mortality rates among 1-year child group and 2-year child group. If you want to compare baby boys only, you'd need to gather data for the boys, excluding the girls. A lower age doesn't necessarily correlate with a higher survival...
by SMMamun
Tue Feb 28, 2017 3:39 pm
 
Forum: Social Lounge
Topic: Probability-?
Replies: 1
Views: 252

Re: BDMO REGIONAL 2015

How did you find 14 number(s)? Did you rather mean 24? How can you find the sum 126 if you take one of the numbers to be 3?

Anyway, the phrase "the sum of any two among them" is ambiguous and does not seem to clarify what the question setters actually asked for.
by SMMamun
Tue Feb 07, 2017 4:32 pm
 
Forum: Divisional Math Olympiad
Topic: BDMO REGIONAL 2015
Replies: 5
Views: 681

Re: BDMO NATIONAL JUNIOR 2012/03

One of the three cases will happen each day:
Rainy morning, Clear afternoon
Clear morning, Rainy afternoon
Clear morning, Clear afternoon

Right?

Can you now assign variable(s) to the no. of days in each case and relate the variables with 11, 16 and 13 in some equations?
by SMMamun
Mon Feb 06, 2017 8:24 pm
 
Forum: National Math Olympiad (BdMO)
Topic: BDMO NATIONAL JUNIOR 2012/03
Replies: 2
Views: 204

Re: Geometry

No, it doesn't depend on anyone's personal consideration of diagonals. Sides are not diagonals, and diagonals are not lines. These two facts don't change with our opinions. :)
by SMMamun
Mon Jan 30, 2017 9:48 pm
 
Forum: Divisional Math Olympiad
Topic: Geometry
Replies: 10
Views: 713

Re: Geometry

The way you are counting 1. views certain side(s) as diagonal(s). For example, if A and B are adjacent vertices, then AB is a side, not a diagonal. You might argue that no pair of the four points (A, B, C and D) is adjacent, but when you generalize the counting for 2013 sides by choosing any group o...
by SMMamun
Mon Jan 30, 2017 9:30 pm
 
Forum: Divisional Math Olympiad
Topic: Geometry
Replies: 10
Views: 713

Re: Geometry

Why will any 4 points give 3 intersecting points of diagonals? Any group of 4 points will generate 2 unique diagonals, and the 2 diagonals will intersect at 1 point.
by SMMamun
Sun Jan 22, 2017 6:47 pm
 
Forum: Divisional Math Olympiad
Topic: Geometry
Replies: 10
Views: 713

Re: A problem of BdPhO'17

Write the decay equation and apply the "law of conservation of momentum" to find the ratio. You may wish to apply "relativistic" momentum in your equation, depending on the level for which the problem has been devised.
by SMMamun
Mon Jan 09, 2017 4:04 pm
 
Forum: Physics
Topic: A problem of BdPhO'17
Replies: 5
Views: 554

Re: BDMO 2016 6No

@ siwomcre, what is the result if you can use only the digits 0, 1 and 2 (NOT ALL of 0 – 9) in the circles?
by SMMamun
Fri Jan 06, 2017 4:05 pm
 
Forum: Junior Level
Topic: BDMO 2016 6No
Replies: 6
Views: 513
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