A knife weighs as much as two spoons.
Three spoons weigh as much as a knife and a fork.
A plate weighs as much as a knife and a spoon.
A fork weighs four ounces.
How much does the spoon weigh?
How much does the knife weigh?
How much does the plate weigh?
Solution to the Problem:
The spoon weighs 4 ounces, the knife weighs 8 ounces,and the plate weighs 12 ounces.
Let s = weight of the spoon
Let f = weight of the fork
Let k = weight of the knife
Let p = weight of the plate
Then write the equations:
k = 2s
3s = k + f
p = k + s
f = 4
Subsituting equations 1 and 4 into equation 2, we get 3s = 2s + 4
So s = 4
Therefore, k = 2s = 2(4) = 8
And finally, p = 8 + 4 = 12
Correctly solved by:
| 1. Colin (Yowie) Bowey | Beechworth, Victoria, Australia |
| 2. Ivy Joseph | Pune, Maharashtra, India |
| 3. Taylor Balding |
Redlands Middle School, Grand Junction, Colorado |
| 4. Noell Kaiser |
Mountain View High School, Mountain View, Wyoming |
| 5. Anna T. Vice |
Landon School, Bethesda, Maryland |