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12th October 2017
02:55pm BST
Think you're the bees knees when it comes to IQ? There's a very simple test that can measure your brainy ability, and even though there's only three questions, it's a LOT harder than it seems.
The test was designed to measure people's tendency to override an incorrect "gut" response and engage in further reflection to find a correct answer.
Think carefully, 'cos even 20% of Harvard students have scored zero.
Can you answer them correctly?
(1) A bat and a ball cost €1.10 in total. The bat costs €1.00 more than the ball. How much does the ball cost? _____ cents
(2) If it takes 5 machines 5 minutes to make 5 widgets, how long would it take 100 machines to make 100 widgets? _____ minutes
(3) In a lake, there is a patch of lily pads. Every day, the patch doubles in size. If it takes 48 days for the patch to cover the entire lake, how long would it take for the patch to cover half of the lake? _____ days
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(1) 5 cents (not 10) (2) 5 minutes (not 100) (3) 47 days (not 24)
Extra explanation
(1) A bat and a ball cost €1.10 in total. The bat costs €1.00 more than the ball. How much does the ball cost? _____ cents
Say the ball costs X. Then the bat costs €1 more, so it is X + 1. So we have bat + ball = X + (X + 1) = 1.1 because together they cost €1.10. This means 2X + 1 = 1.1, then 2X = 0.1, so X = 0.05. This means the ball costs 5 cents and the bat costs $1.05
(2) If it takes 5 machines 5 minutes to make 5 widgets, how long would it take 100 machines to make 100 widgets? _____ minutes
If it takes 5 machines 5 minutes to make 5 widgets, then it takes 1 machine 5 minutes to make 1 widget (each machine is making a widget in 5 minutes). If we have 100 machines working together, then each can make a widget in 5 minutes. So there will be 100 widgets in 5 minutes.
(3) In a lake, there is a patch of lily pads. Every day, the patch doubles in size. If it takes 48 days for the patch to cover the entire lake, how long would it take for the patch to cover half of the lake? _____ days
Every day FORWARD the patch doubles in size. So every day BACKWARDS means the patch halves in size. So on day 47 the lake is half full.
