Puzzle #23 6/1/2000Referring to the diagram below, line AB=12, Line BC=4, Line DB =3 and Line DB is perpendicular to Line AC. What is the diameter of the circle?
ANSWER
Puzzle #22 5/1/2000In the card game "Bridge", each player receives 13 cards. What is the probability that you would be dealt a hand containing no cards higher than a 10 ?
ANSWER
ANOTHER METHOD
36*35*34*33*32*31*30*29*28*27*26*25*24which equals .003638961035.... or about 1 in 275. Pretty good agreement. Puzzle #21 4/2/2000A small boat is floating in a swimming pool. You have a rock which you
will throw into the pool. Will the water level rise
ANSWER
We can
use some actual figures if you wish. Rocks are about 2.5 times
the density
of water. Let's suppose the rock's volume is 125 cubic inches.
Water
weighs 62.4 pounds per cubic foot = 1728 cubic inches. (hmmm 1728.
Isn't
that the domain name of Puzzle #20 3/1/2000An Alphaland Lottery game is played by choosing a 4 digit number. (Any number from 0000 through 9999). On one night, the winning number was exactly the same as the previous night's number. This prompted the Alphaland Lottery Director to say "Since the odds of picking the correct 4 digit number are 1 in 10,000, then the odds of the same number occurring 2 nights in a row are 1 in 100,000,000" (10,000 times 10,000). Was the Director's statement correct?
ANSWER Puzzle #19 2/1/2000There recently was a total lunar eclipse, so here is something appropriate. The Sun has a diameter of 864,000 miles, the Earth to Sun distance is 93,000,000 miles, and the Earth's diameter is 8,000 miles. What is the length of the Earth's shadow ?
ANSWER
Draw line 'AB' from the 'top' of the Sun to the 'top' of the Earth then draw a line from point B to point C. This forms a right triangle whose sides are 428,000 and 93,000,000 miles. (Notice that
line AC is NOT 432,000 miles (the Sun's radius) because the radius of the Earth
must be subtracted from this distance. The ratio of the sides of the
triangle just formed is .004602150538 (428,000 ÷ 93,000,000). Puzzle #18 1/9/2000What 2 numbers (neither of which contain any zeroes) when multiplied together equal 1,000,000,000 ?
ANSWER
Puzzle #17 1/3/2000A jar contains quarters, dimes and nickels totaling $12.90. The total number of coins in the jar is 127 and there are 3 times as many dimes as there are nickels. How many quarters, dimes and nickels are there?
ANSWER
Puzzle #16 12/26/1999Summing the powers of 2, using each power only once, any positive integer may be obtained.
For example using the numbers 1, 2, 4, 8, 16, and 32 any
number from 1 through 63 can be formed.
ANSWER
2 The sum of the above 7 numbers equals 1,000,000.
Puzzle #15 12/19/1999The Verrazano-Narrows Bridge in New York City spans 4,260 feet between 2 towers which are each 690 feet tall. To allow for the curvature of the Earth, how much further apart must the tops of the towers be from the distance at the bottom of the towers?
ANSWER Puzzle #14 12/12/1999Returning to our Alphaland lottery (see Puzzle #13), when 3 of 6 numbers match the winning number, you win a free ticket. What is the probability of getting 3 out of the 6 winning numbers?
ANSWER Puzzle #13 12/05/1999To play the lottery in mythical Alphaland, 6 numbers are selected out of 36. In how many ways can 6 numbers be chosen from 36? (Order is NOT important, meaning 1 2 3 4 5 6 is the SAME selection as 2 3 4 5 6 1, etc.)
ANSWER
Puzzle #12 11/28/1999What is the probability that 7 people chosen at random would have been born on a different day of the week? (That is to say, 1 born on Sunday, 1 on Monday, etc.)
ANSWER
Puzzle #11 11/21/1999
Scientists define the half-life of a substance as the time in which it
will lose
half of its radioactivity. For example, a substance with a
half-life of 10 days will have 50% of its radioactivity in 10 days, 25% in
20 days, 12.5% in 30 days and so on.
ANSWER
Puzzle #10 11/14/1999The mythical town of Alphaville had a population of 10,000 people in 1930. Since then, the population has doubled every 23 years. (For example in 1953, the population equaled 20,000; in 1976 it was 40,000; in 1999, it was 80,000 and so on). What was the population in 1980 ? ANSWER
Since the Alphaville population doubles every 23 years, the population at any
one time can be expressed as:
Puzzle #9 11/07/1999When the Sun, Earth and Mars 'line up' (in that order), Mars is said to be in 'opposition'. Earth takes 365.25 days to orbit the Sun and Mars takes 687.0 days. How much time elapses from 1 such opposition to the next? (Astronomers call this the 'synodic period' of Mars). ANSWER The Earth moves at .985626283 degrees per day (360 ÷ 365.25).
Puzzle #8 10/31/1999Ever wonder how a mountain's height is determined, especially when a tape measure cannot be brought to the peak nor can it be brought to the inside of the base of the mountain? Well, here is one way to do it (assume we are working on level ground and using a transit exactly 5 feet off of the ground). From a certain distance, the mountain peak has an angular elevation of 40 degrees. Moving precisely 1,000 feet closer to the mountain, its angular elevation is now 42 degrees. What is the height of the mountain? ANSWER
The distance from the 2nd measurement will be called 'x'. The distance from the 1st measurement is therefore '1000 plus x'. We now form the 2 equations: 1) tan 40 = h ÷ (1000 + x) OR h=tan 40 * (1000 + x) Where 'h' is the height of the mountain.
Since h is equal to both equations then, Puzzle #7 10/24/1999A triangle has sides of 50, 70 and 80. What are its angles? ANSWER Draw a triangle diagram so that the 50 is on the left, 70 is on the right and the base is 80. Now draw a perpendicular to the base. This perpendicular will have a height 'h' another side 'x' and a hypotenuse of 50.
From the Pythagorean Theorem, we know that h
By substitution, we obtain h=43.30127019.
Puzzle #6 10/17/1999One pipe can fill a water tank in 50 minutes. Another pipe can fill the same water tank in 40 minutes. How much time would it take if both pipes were to fill the same water tank at the same time ? ANSWER There is a formula for this type of problem but just by using logic, the answer is easily obtained. Assume the tank is 50 gallons. So the 'slow' pipe can fill it up at a rate of 1 gallon per minute. The 'fast' pipe can fill it up at a rate of 1.25 gallons per minute. Therefore, with both pipes working together, the tank is filling at a rate of 2.25 gallons per minute. Since it is a 50 gallon tank, then it will fill up in (50 ÷ 2.25) minutes or 22 minutes and 13⅓ seconds. If you want to use the formula, it is (Rate1 x Rate2) ÷ (Rate1 + Rate2) = Time.
Puzzle #5 10/10/1999An employee is to be rewarded with a $250 bonus AFTER TAXES have been deducted. If the federal tax is 15%, the state tax is 10% and the Social Security is 7.5 % what must the GROSS PAY be in order for the net pay to be $250 ? ANSWER: Adding the 3 tax rates together gives us a total tax rate of 32.5%.
Puzzle #4 10/03/1999Twelve is the smallest positive integer that can be divided by the integers 1, 2, 3 and 4 with no remainder. What is the smallest positive integer that can be divided by 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 without any remainder? ANSWER: This number would have to have as its factors 1, 2, 3, 4, 5, etc.
Since any number has 1 as a factor, we don't need it. 2 x 3 x 2 x 5 x 7 x 2 x 3 = 2,520.
Puzzle #3 9/26/1999This one is a 'classic' (and even Marilyn Vos Savant got it wrong - no kidding). If a chicken and a half can lay an egg and a half in a week and a half, how many eggs would one chicken lay in a month and a half (6 weeks) ? ANSWER: The common mistake is to reduce all three quantities to 1 However, if you think carefully about it, this is not the case.For example, imagine you have 8 painters in your 8 room house and they finish in 8 hours. Would this mean 1 painter could paint 1 room in 1 hour? Heck no! One painter can paint one room in EIGHT HOURS.
Returning to the puzzle, we then can say that one chicken lays one egg in a
WEEK AND A HALF. Puzzle #2 9/17/1999A square piece of wood measures 2 feet on each side.
ANSWER: Construct a square in the 'upper left' side of the square. Each of the sides of this square would be 1 foot because the piece of wood is 2 feet square. Using the Pythagorean Theorem, the diagonal of this smaller square would be the square root of 2 or 1.414213562. Now if we draw a line at the upper left to represent one of the sides of the octagon, it would 'slice' the diagonal at precisely the 1 foot mark with the remaining segment of the diagonal equal to .414213562 feet.
This segment is precisely one half the length of 1 of the sides of the octagon because it is part of a 90-45-45 triangle. Therefore, each of the octagon's sides would equal .828427124 feet or 9.941125497 inches.
WOW - were those explanations lengthy or what ????????????
Puzzle #1 9/12/1999This is not as simple as it appears at first glance. A car travels at 60 miles per hour over a certain distance. The car makes the return trip over the exact same distance at 30 miles per hour. What is the average speed of the car?
ANSWER:
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