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You have six numbers in increasing order and the median is always the middle number. If there is, as it is here, an even number of numbers you have to add the third and the fourth number and divide this sum by two:
(6+8)/2=7
- by Nermal
Wed Sep 16, 2009 1:53 am- Forum: Problem Solving
- Topic: PS - median
- Replies: 4
- Views: 1453
@acenikk:
OBD is 30° because OBD is an isoceles triangles with two sides of radius r. If the sides are of the same length the angles have to be of the same measure.
- by Nermal
Tue Sep 15, 2009 7:17 am- Forum: Problem Solving
- Topic: Length of an arc
- Replies: 7
- Views: 1985
- by Nermal
Tue Sep 15, 2009 1:58 am- Forum: Data Sufficiency
- Topic: Is side BC parallel to DE ?
- Replies: 14
- Views: 2500
The formula you were applying refers to the angle at the origin of the circle.
As you can see in the graphic attached, the angle has to be 120°.
Then you can plug in: 2pi*r*120/360=4pi
r=6
pi*r^2=pi*6^2=36pi
- by Nermal
Mon Sep 14, 2009 6:20 am- Forum: Problem Solving
- Topic: Length of an arc
- Replies: 7
- Views: 1985
IMO E There is a quick way of solving this: Let the number of day workers be equal to 100%=1 Let the number of boxes each day worker loads be equal to 100%=1 So the number of boxes loaded by the day worker crew is 1*1=1 Now the number of night workers is 3/4 of the number of day workers and the numb...
- by Nermal
Mon Sep 14, 2009 5:46 am- Forum: Problem Solving
- Topic: complicated problem
- Replies: 2
- Views: 1314
I thought my my way through this problem and looked for a mathematical reasoning afterwards. What I found was the so called RAR-rule of similar triangles. It says that triangles are similar (similar meaning having the same measures of angles but different side lenghts) when one angle is the same (he...
- by Nermal
Mon Sep 14, 2009 2:42 am- Forum: Data Sufficiency
- Topic: Is side BC parallel to DE ?
- Replies: 14
- Views: 2500
- by Nermal
Mon Sep 14, 2009 2:30 am- Forum: Problem Solving
- Topic: PS - integer factorial
- Replies: 5
- Views: 4069
- by Nermal
Mon Sep 14, 2009 2:29 am- Forum: Problem Solving
- Topic: Could any one explain this math question from Princeton ?
- Replies: 3
- Views: 1146
Your method is correct, you just have to go on. I usually pick numbers: first: x=100 x+10%=110 second: (x+10%)+20%=132 Now we want to know by what percent we have to drop 132 in order to get 100. In total numbers we have to drop by 132-100=32 Now we want to know what fraction 32 of 132 is: 32/132=0,...
- by Nermal
Sun Sep 13, 2009 10:55 am- Forum: Problem Solving
- Topic: Could any one explain this math question from Princeton ?
- Replies: 3
- Views: 1146
we need niether of the options. it follows from the stem itself that DE is parallel to BC and is equal to 1/2 BC comes from the mid-point theorem of triangles: a line joining the midpoints of a triangle is parallel to the third side and is half the length of the 3rd side. Of course we need both of ...
- by Nermal
Sun Sep 13, 2009 10:37 am- Forum: Data Sufficiency
- Topic: Is side BC parallel to DE ?
- Replies: 14
- Views: 2500
IMO E.
I drew a table.
This shows that both statements together do not give the information on whether those 10 cars that have no stereo actually have power windows.
- by Nermal
Sun Sep 13, 2009 3:13 am- Forum: Data Sufficiency
- Topic: How many of the 60 cars sold last month by a certain dealer
- Replies: 2
- Views: 2913
- by Nermal
Sun Sep 13, 2009 2:50 am- Forum: Data Sufficiency
- Topic: Each member's contribution is to be $4.
- Replies: 1
- Views: 1318
- by Nermal
Sun Sep 13, 2009 2:22 am- Forum: Data Sufficiency
- Topic: Is side BC parallel to DE ?
- Replies: 14
- Views: 2500
Is statement 2 saying x=6 or x=60?
Then it would be a 30-60-90-triangle and with the information of statement 1 you could solve for the distance from B to the ground.
IMO C
- by Nermal
Sun Sep 13, 2009 2:16 am- Forum: Data Sufficiency
- Topic: Squirrel on a Wire
- Replies: 3
- Views: 1735
IMO E (50)
You can express the equation a+b+c+d=180 in terms of a only.
a+4a+a-20+2a=180
8a-20=180
8a=200
a=25
b=2a=2*25=50
- by Nermal
Sun Sep 13, 2009 2:03 am- Forum: Problem Solving
- Topic: Angles on a Line
- Replies: 4
- Views: 1347