1.John, Mark, and Henry are three brothers. Interestingly, their current age is prime. What’s more interesting is that difference between their ages is also prime. How old are they?
Answer
Mark is 2, John is 5, and Henry is 7. Age diff 7 – 2 = 5 is prime; 7 – 5 = 2 is prime; 5 – 2 = 3 is prime.
2.Divide 20 by half and add 30, what do you get?
Answer
Seventy, because 20 divided by ½ = 10 + 30 = 70.
3.Joe has ten coins totaling $1.19. From these coins, he cannot make exact change for a dollar, half-dollar, quarter, dime, or nickel. What coins does he have?
Answer
A half-dollar, a quarter, four dimes, and four pennies.
4.There are twelve kids in a classroom. Six kids are wearing socks and 4 are wearing shoes. Three kids are wearing both. How many have bare feet?
Answer
Five kids have bare feet.
5.There are 25 red balls, 47 green balls. and 3 blue balls in a basket. There is a blind man. What is the minimum number of balls that the blind man has to pick to make sure that there are at least 2 balls of different colors?
Answer
48 balls. There is a small chance he may pick up 47 green balls in a row.
6.One is to three as three is to five and five is to four and four is the magic number. What is the pattern?
Answer
letters in it. (If you try more numbers, they will always come back to the number four, so four is the magic number.)
7.Nathan has 8 bricks. Seven of them weigh the same amount and one is slightly heavier. Using a balance scale, how can Nathan find the heavier brick in two weighings?
Answer
First, he splits them in to piles of 3, 3, and 2 bricks. Then he weighs both groups of 3 with each other. If they balance, he knows the brick is one of the 2 not-weighed bricks and he can weigh them to find the heaver one. If the stacks of 3 bricks do not balance, he will weigh 2 of the 3 bricks. If they balance, he will know the brick left not weighed is heavier, or if they do not balance, he will find the heavier one.
8.Sally and Sarah were preparing to have a water balloon fight. “No Fair” cried Sally, “You have 3 times as many as I do!” Sarah said “Fine!” and gave Sally 10 more balloons. “Still not fair!” argued Sally, “You still have twice as many as I do.” How many more balloons must Sarah give Sally for them to have the same number?
Answer
Sarah must give Sally another 20 water balloons, giving them each 60. Sally started with 30 water balloons and Sarah with 90.
9.Two travelers spend from 12 o’clock to 6 o’clock walking along a level road, up a hill, and back again. Their pace is 4 mph on the level, 3 mph uphill, and 6 mph downhill. How far do they walk and at what time do they reach the top of the hill?
Answer
They walk 4 miles and reach the top of the hill at half past three.
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