- 1 Dollar, 50 Coins [02/22/2002]
I'm looking for two ways to change a dollar bill using exactly 50
- 21 Nickels, Dimes, and Pennies in a Dollar [11/8/1994]
How can you have 21 coins of nickels, dimes, pennies that equal one
dollar? No quarters. My son and I need an explanation.
- 25 Coins for a Dollar [02/13/2003]
I need 25 coins for my dollar. What are they?
- 25 Coins in a Dollar [05/07/2001]
Carlos has 25 coins whose total is $1.00. What are the coins?
- 25 Coins in a Dollar [08/16/2001]
How can you get a dollar using 25 coins? Find five combinations.
- 50 Coins = One Dollar [02/24/1997]
How can you make up one dollar using 50 coins?
- 55 Cents, Seven Coins [05/15/2001]
How can you get 55 cents with seven coins (quarters, dimes, nickels or
pennies only) eight ways?
- 5 Coins = 55 Cents [01/28/1997]
I have five coins in my pocket. Together they are worth 55 cents. What
coins do I have?
- About Base Five [10/22/2001]
I don't understand anything about bases.
- Adding and Subtracting Fractions [10/25/1999]
Can you help me learn to add and subtract fractions?
- Adding Decimals [05/26/1998]
I can't figure this out: 894.56 + 4563.5 = ?
- Binomial Experiments [09/05/2003]
How can I explain the binomial distribution to my six grade math class?
- Binomial Probability [04/14/1999]
A multiple-choice exam probability question.
- Boy or Girl: Two Interpretations [01/03/2000]
How can the probability be 2/3 of a boy in a two-child family having a
sister? Shouldn't it be 1/2?
- Breaking One Big Problem into Several Smaller Ones [09/11/2003]
How can I change a dollar into exactly 26 coins?
- Bus Fare Problem [02/12/1998]
Each of 5 students paid a fare with 5 coins, for a total of $21.83. How
many pennies did the bus driver receive?
- Cascading Coffee Confusions [09/17/2017]
A teen and her family disagree about the likelihoods of her coffee order going awry.
Drawing out several models, Doctor Ian clarifies how to properly weight two outcomes
from three distinct sequences of events.
- Change for a Dollar [11/05/1999]
When changing a dollar bill, you can give 1 coin (1 silver dollar), 2
coins (2 half-dollars), 3 coins (2 quarters and 1 half-dollar), and so
on. What is the least positive number of coins that is impossible to give
as change for a dollar bill?
- Change for a Dollar [01/22/2001]
Could you please tell me the two hundred plus ways in which coins are
used to make change for one dollar?
- Coin Combinations Quickened by Process of Elimination [11/04/2013]
A student seeks a method for efficiently attacking a puzzle that involves partitioning
sums of coins. Doctor Greenie suggests he reverse his thinking and work backwards.
- Coin Combinations to Make a Dollar [11/12/1996]
What is the number of combinations you need to get a dollar using
pennies, nickles, dimes, quarters, and half dollars?
- Coin Landing on Edge [11/29/2001]
What are the chances of a coin landing on edge? A Canadian copper penny,
- Coin Patterns [08/26/2003]
Each of four rows of coins has exactly one penny, one nickel, one
dime, and one quarter. No row, either horizontal, vertical, or
diagonal, has more than one coin of each kind. How are the coins
- Coin Recognition [11/20/2002]
My son is working on money in class and I am looking for something
that shows what each coin looks like.
- Coins in a Square Array [7/8/1996]
I left some coins on the table in a square array and now there are only
two left... prove that the butler lied.
- Coins in Change under $1 [03/13/2001]
Is there a formula or equation for determining the smallest number of
coins a person could receive when given change less than $1.00?
- Coin Specifications [09/24/2001]
Approximately how many nickels does it take to make a pound? How many dimes? Pennies?
- Coin Toss Probability [05/26/2007]
If a coin is tossed 100 times, what is the probability that you get
less than or equal to 40 heads?
- Coin With 11 Sides and a Constant Diameter [10/20/2007]
I was told that one of the reasons why a Canadian Loonie coin is
11-sided is that it rolls better than a 10-sided coin. Why is that?
- Collision of Two Circular Objects [02/02/2002]
If I have two coins moving across a frictionless surface, knowing their
velocity and angles, how can I find the angle of each object after they
- Combinations of Coins [1/28/1996]
If I had 6 coins in my pocket, how many combinations could I have?
- Conditional Probability [12/31/1997]
I tutor probability and statistics and people seem to be confused by the
use of the multiplication rule in conditional probability...
- Counterfeit Coin Challenge [05/12/2007]
In a set of 13 coins, either zero or two of them are counterfeit and
are lighter. You must identify the counterfeit coins, if any, after
four or fewer weighings on a balance scale.
- Counting Money [06/28/1997]
How can I learn to count money better?
- Different Combinations of Coins [2/18/1996]
Francisco has some change in his pocket. He gives his friends three clues
to see if they can guess how much he has: the coins equal exactly one
dollar; he has no more than 100 coins; he has at least one coin. What
combination of coins can Francisco have in his pocket?
- Dimes and Quarters Puzzle [11/5/1994]
Jessica has 16 dimes and quarters. Whitney has twice as many dimes and
1/3 as many quarters as Jessica has. They both have the same amount of
money. What coins does each have?
- Distribution of Cards in Bridge [05/03/2001]
In bridge, it often happens that you and your partner have 9 cards of a
suit between you. In all the bridge books that I have read, it is stated
that the probability of the remaining 4 cards splitting 2-2 is 40.7%. Can
this be proven?
- Distributive Property [10/29/1997]
I don't understand the Distributive Property at all.
- Do Prior Outcomes Affect Probabilities of Future Ones? [05/26/2008]
I know that the probability of flipping a coin and getting a head is
1/2. But if I've gotten ten straight tails, isn't it more likely that
the next one will be a head?
- Estimation in 3rd Grade [12/16/1996]
How do you learn to estimate? What is its importance?
- Explaining Bayes' Theorem [03/22/1999]
I need an easy-to-understand explanation of Bayes' Theorem to begin my
math project for the math fair.
- Factors and Rectangles [06/25/1998]
I'm trying to figure out what a rectangle and factors have in common.
- Finding One Coin of 12 in 3 Steps [8/6/1996]
Given a pile of twelve coins of equal size with one of a different
weight, in three weighings find the unequal coin...
- Finding the Counterfeit Coin (1 of 9) [05/29/1998]
One of nine coins is counterfeit and is lighter or heavier than the
others. How do I locate it in three weighings only?
- Finding the Shape of a Funnel Curve [04/08/2001]
Find the equation of the curve of revolution of a coin leaving a chute.
- Find the Heavier Coin of 12 in 3 Weighings [11/17/1996]
If there are twelve coins in a bag, one of which is either lighter or
heavier than the others, find the fake coin in exactly 3 weighings AND
determine if it is lighter or heavier than the others.
- Five Dollars in Change [10/07/1997]
I need to make $5.00. I have to use 100 coins but I can't use nickels.
- Formula for Nim [02/22/2002]
Is there a formula for the game of Nim?
- Four Safety Match Tips, One General Probability Tip [06/14/2015]
An adult struggles to make heads or tails of a probability problem. Modeling it as a
more familiar question of coin tosses, Doctor Ian lights a way forward.
- Getting More Heads [05/29/2000]
If Bob flips 850 fair coins and Alice flips 851 fair coins, what is the
probability that Alice will get more heads than Bob?