Difficult IQ Test - Answer 20 Questions and Reach 94th Percentile

[Pseudopod]

Difficult "IQ" test

This is a very interesting IQ test. You are basically ranked against all the others who also took the test. There are 20 questions total, but it calculates your percentile as you go. I answered all 20 this afternoon and got 94th percentile, answering 13 of the 20 questions correctly.

I found some of the questions to be MUCH more difficult than normal IQ tests so it was very fun to take.

http://www.mental-testing.com/

If anyone knows how to correctly do #6 (Amelia Earhart problem) please let me know! I thought I did it correctly but it said I gave the wrong answer.

 

[BicycleTree]

I did this a while ago. I got the wrong answer for the Earhart problem (they are not numbered the same on different tests) but then I figured it out: Two planes fly side by side for 1/3 tank, then transfer 1/3 tank and 1 flies back while other flies on. At appropriate time 1 starts flying out to meet Earhart, at distance of 1/3 tank. Again it transfers 1/3 tank and both fly back. So the distance is 1/3 tank (beginning) + full tank + 1/3 tank (end) = 24000. x is the distance of a full tank so 5/3 x = 24000 and x = 14400.

 

[Pseudopod]

Ah of course! Very smart bicycletree!

 

[whozum]

A commuter drives to work 16 miles. Due to traffic, the commuter averages 30 miles per hour on the first 8 miles of the drive. How fast must the commuter go on average on the second half to average 40 miles per hour for the entire drive?

How is this NOT 50?

 

[Berislav]

How is this NOT 50?

Because:


t1 - time for first half
t2 - time for second half
v1-speed for first half
v2-speed for second half

v1=s/(2*t1)
v2=s/(2*t2)

from s/(t1+t2)=40 one can obtain t2, and find that v2=60.

 

[whozum]

Two components, first half is 30, second half is x.
What is x so the two avg to 40

(30+x)/2 = 40
30+x = 80
x = 50

 

[whozum]

I don't see why I'm wrong on half of those, but then again I'm doing them in my head. I still don't get why the method in the post above doesn't work

 

[Berislav]

You can't just find their arithmetic mean.

$$v_{average}=\frac{\Delta s}{\Delta t}=\frac{s}{t_1+t_2}$$

 

[xJuggleboy]

The firs 10 or so questions I ran into were vocabulary questions of words which I have never heard... I had one math problem then 5 or so more vocabulary questions... Not much of a "IQ" test