Brainteasers – Issue 23, 2012

1. The Curly Shuffle

A factory has three CNC machines – each with its own operator. One day a large order is received and Larry quickly boasts “Curly and I can produce all those parts in ten days, but if you let Moe help me instead of Curly, we can do it in 9 days”. Curly is offended, and replies “Forget about Larry, if Moe and I produce the parts, we can finish in 8 days”. How long would it take each CNC operator to produce all the parts on his machine individually?

2. Cable Tie-up I

Can you remove four cable ties from the following arrangement and leave four equal size triangles with no extra “offshoots” or loose ends?

Cable-Tie-Up-1


3. Widgetry

During the morning shift the probability of a widget passing by a certain sensor (on a conveyor belt) in a 20 minute window is 0.9. What is the probability of a widget passing that sensor in a 4 minute window? Please assume a constant probability throughout the shift.


4. Cable Tie-up II

Starting with the arrangement shown above can you move only six of those cable ties and produce a pattern with five (unique) squares? No doubling-up the cable ties or loose ends, please.

Cable-Tie-up-2

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