MATH BRAIN TEASERS

Ne, the bus driver.

On the 1st stop, 5 people get on. On the 2nd stop, 5 people get off and 10 (twice as many as at 1st stop) people get on. On the 3rd stop, 10 people get off. So there are (5 5 + 10 10) 0 passengers left, which leaves the bus driver as the only person on board the bus. Did you answer this riddle correctly?
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This problem has an infinite number of solutions modeled by the equation 8a=7n, where a is the amount of flowers the man starts with and n is the number of flowers he leaves at each grave. The simplest and possibly trivial solution would be to start with 0 flowers and leave 0 flowers at each grave. A more significant solution would be to start with 7 flowers and leave 8 at each grave. Any positive integer multiple of this solution also satisfies the conditions. For example, the man starts with 14 flowers and leaves 16 at each grave; so, 14 doubles to 28, and 28-16= 12; 12 doubles to 24, and 24-16= 8; 8 doubles to 16, and 16-16= 0. The result is the same if the man starts with 21 flowers and leaves 24 flowers at each grave, or starts with 28 and leaves 32. Did you answer this riddle correctly?
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The stones weight 1 pound, 3 pounds, 9 pounds and 27 pounds. These can be used in combination with each other on both sides of the scale to come up with any counterweight from 1 to 40 pounds. Did you answer this riddle correctly?
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9 Did you answer this riddle correctly?
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15 chocolates with resale. 15 then with 15 wrappers you get 5 more chocolates. With 3 wrappers from the 5 new chocolates you get 1 more chocolate. And with these 1 more wrapper and the remaining 2 wrappers you get 1 more chocolate. Hence you get total 15 + 5 + 1 + 1 = 22 Did you answer this riddle correctly?
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Mr. Jackson was 54 and his wife was 18. Now hes 72 and his wife 36. Did you answer this riddle correctly?
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If the girls had been on a standing train, the first girl's calculations would have been correct, but their train was moving. It took 5 minutes to meet a second train, but then it took the second train 5 more minutes to reach where the girls met the first train. So the time between trains is 10 minutes, not 5, and only 6 trains per hour arrive in the city. Did you answer this riddle correctly?
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The train is moving at 40 miles per hour. Imagine that a friend is walking with you. When the train whistle blows, you head away from the train, he heads toward it. When he reaches safety, you will be 6/8 (or 3/4)of the way across the bridge, and the train will have just reached the bridge. For the train to cross 4/4 of the bridge in the time you cross the remaining 1/4, the train must be moving four times your speed. Did you answer this riddle correctly?
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I am a Triangle. Did you answer this riddle correctly?
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Four daughters and three sons. Each daughter has 3 sisters and 3 brothers, and each brother has 2 brothers and 4 sisters.

To figure it out mathematically, you could use the following two equations where G = the number of girls and B = the number of boys:
G 1 = B
2(B 1) = G

Solving for G gives you 4 and plugging that in to G 1 = B gives you a B of 3. Did you answer this riddle correctly?
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The answer is 3

If you got a different number you did the math wrong Did you answer this riddle correctly?
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5 owls and 5 wolves, (not 6 owls because 2 of the eyes and legs are yours).

2 * owls + 2 * wolves = 20 eyes
2 * owls + 4 * wolves = 30 legs
owls + wolves = 10 eyes owls = 10 wolves
owls + 2 * wolves = 15 10 wolves + 2 * wolves = 15 wolves = 5
owls + 5 = 10 owls = 5 Did you answer this riddle correctly?
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When the boats meet for the first time, they have sailed a combined distance that is equal to one length of the lake. When they meet the second time, they have sailed 3 lengths. The elapsed time and the distance for each is three times.

When they meet for the second time, the boat M has sailed 500 x 3 = 1500 yards. Now, this is 300 yards longer than the length of the lake, it must be 1200 yards wide.

The ration between the speed of boat M and boat N is equal to the ratio of the distance that they have sailed before they meet the first time. Did you answer this riddle correctly?
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One big pile. Did you answer this riddle correctly?
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Put three balls on each side of the scale. If the arms are equal, you know the heavy ball is one of the two remaining. If the arms are unequal, take the three balls on the heavier side, pick two and weigh them against each other. Did you answer this riddle correctly?
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