Intelligence Quotient (IQ) tests are standardized test series to valuate human intelligence. Many different type of tests are handled to evaluate human. The Cognitive Reflection Test (CRT) is one of the shortest IQ test in the world. It was developed by psychologist Shane Frederick in 2005. This CRT comprises of only 3 Questions. All the 3 are somewhat tricky.
Question 1 : The Bat and Ball Problem
A ball and a bat costs $1.10 together. The bat costs $1 more than the ball. Then how much does the ball cost???
Question 2 : The Widget-Making Machine Problem
If it takes 5 minutes for 5 machines to make 5 widgets, how long would it take for 100 machines to make 100 widgets???
Question 3 : The Size-Double Lily Pad Patch Problem
There is a patch of lily pads in a lake. Everyday, the patch doubles in size. If it takes 48 days to cover the whole lake, how long would it take to cover half the lake???
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Answer 1 : Let us consider the cost of the ball be 'X'. Then the cost of the bat will be '$1 + X' (because the bat costs $1 more than the ball).
Cost of bat + Cost of ball = $1.10
X + ($1+X) = $1.10
By simplifying, 2X + $1 = $1.10
2X = $0.10
hence, Cost of the ball (X) = $0.05 and Cost of bat ($1+X) = $1.05, total cost = $1.10
Answer 2 : 5 Machines takes 5 minutes to build 5 Widgets. This instance 1 machine each takes 5 minutes to build 1 widget. Hence, 100 machines takes the same 5 minutes to make 100 widgets.
Answer 3 : The patch takes 47 days to cover the entire lake. Everyone might guessed that it would take 24 days. If the area of lake covered by the patches doubles everyday, it would take only one day to cover it from half to fully covered.
Shane Frederick says, "These questions make the people, those who attend the test, very easily come out with an answer, which would probably a wrong one, without proper analysis. That's the reason why I picked these questions for CRT".