Post mathematic related questions here

[Niilesh]

Re: mathematic related questions

Correct, it took me more than half an hour to solve it...

 

[rst]

Re: mathematic related questions

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[Niilesh]

Re: mathematic related questions

^ Can you explain how are they arranged?

 

[rst]

Re: mathematic related questions

I think they are arranged joining each other to form cuboid

 

[Niilesh]

Re: mathematic related questions

Ans is 2?

 

[rst]

Re: mathematic related questions

Can you show your work ???

 

[Niilesh]

Re: mathematic related questions

A = na^2 (a= side length of cube)
V = na^3
=>A^3/V^2 = n

 

[rst]

Re: mathematic related questions

yeah
your work looks fine

A^3/V^2 is the correct answer

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Hint:-
answer is not 8 and 12

 

[Niilesh]

Re: mathematic related questions

the smallest enclosed 2D fig is triangle so probably tetrahedron will be the smallest 3D fig, so ans is 6

 

[rst]

Re: mathematic related questions

I also think the same
with 6 sticks tetrahedron is possible(which can enclose 3D volume)
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[Niilesh]

Re: mathematic related questions

4 min(I Used the concept of relative velocity)

 

[rst]

Re: mathematic related questions

Can you show your work ??

 

[Niilesh]

Re: mathematic related questions

Let 'B' be at rest, then A is coming towards it with velocity '3v'.
At first distance between them is C/2(C=circumference) and to cross B again A will have to travel C distance, since Time is directly proportional to distance(when velocity is constant) so time=2*2= 4min

 

[rst]

Re: mathematic related questions

Yeah
you are right

Also this method is shorter than mine

 

[Niilesh]

Re: mathematic related questions

^ What was your method?
The only method i know other than the relative one is the 'imagination' one

 

[rst]

Re: mathematic related questions

I also used relative velocity method
But instead of 3v
I used distance travel by A= 2v (time x velocity)
distance travel by B= 4v
total distance =6v

In second time they have to move whole circumference
total distance =12v
vt +2vt =12v
t=4 min.

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[Niilesh]

Re: mathematic related questions

Ans is 3
Solution -
1^13 < 2^13
3^13 < 5^13
.
.
. and so on
.
.
.

so, C>B
=>C/2 > B/2 ---(1)

Now, A= C/2 + B/2
=>C>A>B (From equation 1)

 

[rst]

Re: mathematic related questions

great!!
answer is absolutely right
Also with this method one can solve the question in short time

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ans is (B) 3

 

[rst]

Re: mathematic related questions

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[rst]

Re: mathematic related questions

ans is 5
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Let number of units be x
S.P of one unit =60
S.P of x unit =60x
C.P=100

profit=500
S.P - C.P=500
60x- 100 =500
x=10
so number of units =10

C.P increase by 30%
New C.P=130
Let new S.P per unit be y
total S.P=10y (as number of units is 10)
As profit is same
new S.P - New C.P =500
10y - 130 =500
y=63
So new S.P per unit =63
increase percentage in S.P per unit = [(63-60)/60 ] x 100
=[3/60 ] x 100
=5