Riddle #878

logic

Rainy Day Elevators

A man lives on the 44th floor of his building. On rainy days, when he gets home from work, he takes the elevator all the way up to his floor. But on sunny days, he goes up to floor 20 and walks the rest of the way. Why does he do this?
The man is a midget and cannot reach button "44" in the elevator on sunny days. On rainy days he has his umbrella with him and is able to use it to press the button.
93.05 %
36 votes

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logicmath

The Circular Lake

A swan sits at the center of a perfectly circular lake. At an edge of the lake stands a ravenous monster waiting to devour the swan. The monster can not enter the water, but it will run around the circumference of the lake to try to catch the swan as soon as it reaches the shore. The monster moves at 4 times the speed of the swan, and it will always move in the direction along the shore that brings it closer to the swan the quickest. Both the swan and the the monster can change directions in an instant. The swan knows that if it can reach the lake's shore without the monster right on top of it, it can instantly escape into the surrounding forest. How can the swan succesfully escape?
Assume the radius of the lake is R feet. So the circumference of the lake is (2*pi*R). If the swan swims R/4 feet, (or, put another way, 0.25R feet) straight away from the center of the lake, and then begins swimming in a circle around the center, then it will be able to swim around this circle in the exact same amount of time as the monster will be able to run around the lake's shore (since this inner circle's circumference is 2*pi*(R/4), which is exactly 4 times shorter than the shore's circumference). From this point, the swan can move a millimeter inward toward the lake's center, and begin swimming around the center in a circle from this distance. It is now going around a very slightly smaller circle than it was a moment ago, and thus will be able to swim around this circle FASTER than the monster can run around the shore. The swan can keep swimming around this way, pulling further away each second, until finally it is on the opposite side of its inner circle from where the monster is on the shore. At this point, the swan aims directly toward the closest shore and begins swimming that way. At this point, the swan has to swim [0.75R feet + 1 millimeter] to get to shore. Meanwhile, the monster will have to run R*pi feet (half the circumference of the lake) to get to where the swan is headed. The monster runs four times as fast as the swan, but you can see that it has more than four times as far to run: [0.75R feet + 1 millimeter] * 4 < R*pi [This math could actually be incorrect if R were very very small, but in that case we could just say the swan swam inward even less than a millimeter, and make the math work out correctly.] Because the swan has less than a fourth of the distance to travel as the monster, it will reach the shore before the monster reaches where it is and successfully escape.
93.70 %
40 votes

funnylogicmath

Maths magic riddle

Tarun Asthnaiya go to his office by local train. However nearby train station is quite far from his place and he used to drive his bike to train station daily with an average speed of 60km/hr. One day at halfway point he relized that due to heavy traffic he got late having average speed of just 30km/hr. How fast he must drive for the rest of the way to catch my local train?
The train is just about to leave the station and there is no way Tarun will be able to catch it this time.
92.86 %
35 votes

funnylogicshort

Volume of the pizza

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?
pi * z * z * a
92.67 %
34 votes

logicmathshort

Number 45

Can you write number 45 using only the number 4?
44+44/44
92.02 %
31 votes

logicshortwhat am I

Present in sun, but not in rain

Only one color, but not one size. Stuck at the bottom, yet I easily fly. Present in sun, but not in rain. Doing no harm, and feeling no pain. What Am I?
Shadow.
91.04 %
47 votes

cleanlogicmathshort

Hards maths number

Create a number using only the digits 4,4,3,3,2,2,1 and 1. So I can only be eight digits. You have to make sure the ones are separated by one digit, the twos are separated by two digits the threes are separated with three digits and the fours are separated by four digits.
41312432.
89.07 %
38 votes

logicmysteryscary

Cottage Life

A wealthy man lives alone in a small cottage. Being partially handicapped, he had everything delivered to his cottage. The mailman was delivering a letter one Thursday when he noticed that the front door was ajar. Through the opening he could see the man's body lying in a pool of dried blood. When a police officer arrived he surveyed the scene. On the porch were two bottles of warm milk, Monday's newspaper, a catalog, flyers, and unopened mail. The police officer suspects it was foul play. Who does he suspect and why?
The police officer suspects the newspaper delivery person. The absence of Tuesday's and Wednesday's newspaper indicates that the delivery person knew there was no one there to read it.
73.55 %
138 votes