World's 200 Hardest Brain Teasers (6 page)

175. What is the opposite of EBULLIENT?

(a) aggressive

(b) tranquil

(c) compliant

176. How many integers between 10 and 100 are divisible by 3?

177. The volume of a cube is 27. What is the sum of the length of all its edges?

178. What is the next letter in the following series:

a c d b e g h i f j l m n ?

(a) k

(b) l

(c) m

(d) n

(e) o

179. It takes Jim 4 hours to do a job. It takes Tom 2 hours to do the same job. How many such jobs could they do together in 4 hours?

180. A survey of 50 people who can write showed that 20 could write only with their left hand and 10 could write with either hand. How many could write with their right hand?

(a) 30

(b) 20

(c) 25

(d) 10

(e) 40

181. The average of the number 10 and some unknown number,
x
, is divided by the sum of 10 and
x
. The result is 1/2. What is the value of
x?

182. The difference between the greatest and smallest two-digit even integers that are exactly divisible by 4 is:

(a) 82

(b) 84

(c) 96

(d) 88

(e) 80

183. How far would a bicycle wheel of diameter 2 feet roll in 700 revolutions?

184. A typist increased her speed from 60 words per minute to 80 words per minute. What percent did her speed increase?

185. If a sheet of cardboard has an area of 186 square inches, and two pieces each measuring 6 inches x 3 inches are cut out, what is the area of the remaining cardboard?

186. Put the following statements in the correct order:

(a) The price of gasoline doubles.

(b) A man cancels an order for a car.

(c) A man’s car is totally demolished in an accident.

(d) A man orders a compact car.

(e) A man orders a high horsepower car.

187. COURT : LITIGATION ::

(a) settlement : client

(b) prayer : litany

(c) judge : lawyer

(d) reconciliation : dispute

(e) tournament : joust

188. A certain orchestra has exactly three times as many string musicians as musicians playing wind instruments. Which of the following can be the combined number of string and wind musicians in this orchestra?

(a) 27

(b) 28

(c) 29

(d) 30

(e) 31

189. OBOE : BASSOON ::

(a) viola : cello

(b) trumpet : violin

(c) mountain : peak

(d) globe : city

(e) antonym : pseudonym

190. Carl has four times as many quarters as Steve and three times as many quarters as William. If Carl, Steve, and William have a total of less than 200 quarters, what is the greatest number of quarters that Carl could have?

191. Jane is three times as old as Ann; three years ago, Ann was a year younger than Joyce is now. If Ellen is twice as old as Ann, list the four girls in descending age order.

192. A girl has exactly enough money to buy three sweaters and two skirts, or three skirts and no sweaters. All sweaters are the same price, and all skirts are the same price. What is the maximum number of sweaters she can buy if she buys only one skirt?

193. Beads are strung onto a necklace in this order: red, white, green. A design that begins on red and ends on white could be composed of the following number of beads:

I. 17

II. 29

III. 35

(a) I only

(b) III only

(c) II and III only

(d) I and III only

(e) I, II, and III

194. Put the following statements in the correct order:

(a) A student buys a bicycle.

(b) A student rides to school on the subway.

(c) A student leaves for school at 8:00 AM.

(d) A student leaves for school at 8:30 AM.

(e) The price of a subway fare doubles.

195. LULLABY : CRADLE ::

(a) birth : marriage

(b) barcarole : gondola

(c) song : poem

(d) carol : sonneteer

(e) night : morning

196. It is not true that both Freddie and Susan will be hired by Phoenix labs. Which of the following is possible based on the previous statement?

I Either Freddie or Susan will be hired by Phoenix labs.

II Neither Freddie nor Susan will be hired by Phoenix labs.

III Freddie and Susan will be hired by Phoenix labs.

IV Freddie will be hired by Phoenix labs only if Susan is.

V Either Freddie or Susan will not be hired by Phoenix labs.

(a) I only

(b) II only

(c) III only

(d) IV only

(e) V only

(f) I, II, and V only

197. The perimeter of this figure is:

(a) a whole number

(b) less than 30

(c) greater than 40

(d) 22

(e) 20

198. Which fraction is greater, or are they equal?

OR

199. A soldier has been captured by the enemy. He is so brave that they offer to let him choose how he wants to be killed. They tell him, “If you tell a lie you will be shot, and if you tell the truth you will be hanged.” He can only make one statement. He makes a statement and goes free. What could he have said?

(a) “I will be hanged.”

(b) “I will be shot.”

(c) “I will not be shot or be hanged.”

(d) “I will be shot or be hanged.”

(e) “I am not a liar.”

200. On a street there are 25 houses—10 of the houses have fewer than six rooms, 10 of the houses have more than seven rooms, and 4 houses have more than eight rooms. What is the total number of houses that are either six, seven, or eight rooms?

(a) 5

(b) 9

(c) 11

(d) 14

(e) 15

201. Name twenty English four-letter words that also make an English word when a letter is placed in front of the word.

202. What do these numbers have in common?

111, 112, 115, 128, 132, 135, 144, 175, 212, 216, 224, 312, 315, 384, 432, 612, 624, 672, 735, 816

203. A horse is pulling a cart. It is a known fact that the force that the horse exerts on the cart is equally balanced by the force that the cart exerts on the horse (Newton’s third law). Since both of these forces balance (net “0”), how do the horse and cart move?

204. What is the largest number one can write using only four 4s?

205. What percent of 5 is 20? (65 percent of California students got the answer to this question wrong!)

(a) 25

(b) 40

(c) 100

(d) 200

(e) 400

206. A rectangle is inscribed in a quarter-circle as shown below The radius of the circle is 5 inches. Find the length of the diagonal of the rectangle as shown in the diagram.

207. This problem had baffled three Physics Nobel Prize winners— and it doesn’t seem that hard!

Note: This question is much more difficult than problem 146, where you know that the “odd” ball is heavier than the rest.

Twelve balls are identical in all ways except one has a different weight. Three weighings on a balance scale will not only identify the odd ball, but also tell whether it is heavier or lighter. How many balls must be put on each side of the scale in the first weighing, the second weighing, and the third weighing?

Answer should be in this form (this is only a sample answer, not necessarily the correct one):

First weighing—six against six

Second weighing—three against three

Third weighing—one against one

208. On the
Tonight Show with Johnny Carson,
Carson spent fifteen minutes trying to solve this problem and no one, including himself, could do it!

A teacher shows three very bright students three red hats and two white ones. The students are then blindfolded and the teacher puts one hat on each of their heads and the remaining hats in a closed bag. The first student removes his blindfold and is able only to see the other two students’ hats. He says he cannot say for certain the color of his own hat.

After hearing the first student, the second student removes her blindfold, sees the other two students’ hats, and says that she cannot say for certain the color of her own hat. After thinking and without removing his blindfold, the last student says he knows the color of his hat. Which is false? Note: Any combination of a, b, c, d, and e may be the correct answer.

(a) The third student has enough information to determine the color of his hat without removing his blindfold.

(b) The third student’s hat can be white.

(c) The three students’ hats can be the same color.

(d) Both remaining hats in the bag can be red.

(e) There are exactly four possible combinations of hat colors on the students’ heads.

209. This can be a real brain racker unless you know some important math strategies.

A ship is twice as old as the ship’s boiler was when the ship was as old as the boiler is. The ratio of the boiler’s age now to the ship’s age now is what?

210. Out of 3 females and 3 males, 3 people at random enter an empty room. What is the probability that there are two males and one female in the room now?

1.     A quarter and a nickel

Be careful of what the wording says: One is not a nickel, but the other is. This is a standard trick in the English language. When you say, “one of them is not a nickel,” it doesn’t mean that both are not nickels. The key strategy is to pay attention to the wording and not assume anything. The mind gets lured into a process that seems natural. So if you hear someone say, “one of them is not a nickel,” you may assume that the person means that both are not nickels. But the statement “one is not a nickel” does not imply that the other cannot be a nickel.