This is esay to do when you realize the the speed of mowing is addtive. This is if John mows at 1 lawn / (2/3) hour and Gerge mows at 1 lawn / 1hour, the total speed of mowing is:
1 / (2/3) + 1 = 3/2 + 1 = 5/2
=> 5/2 of lawn per hour
Now, the time is calcualted as the amount of lawn divided by the speed:
1 lawn / (5/2 lawn/hour) = 2/5 hour.
Answer: 2/5 of an hour.
Answer:
B. The area of 26 meters.
Step-by-step explanation:
Let's call the stamps A, B, and C. They can each be used only once. I assume all 3 must be used in each possible arrangement.
There are two ways to solve this. We can list each possible arrangement of stamps, or we can plug in the numbers to a formula.
Let's find all possible arrangements first. We can easily start spouting out possible arrangements of the 3 stamps, but to make sure we find them all, let's go in alphabetical order. First, let's look at the arrangements that start with A:
ABC
ACB
There are no other ways to arrange 3 stamps with the first stamp being A. Let's look at the ways to arrange them starting with B:
BAC
BCA
Try finding the arrangements that start with C:
C_ _
C_ _
Or we can try a little formula; y×(y-1)×(y-2)×(y-3)...until the (y-x) = 1 where y=the number of items.
In this case there are 3 stamps, so y=3, and the formula looks like this: 3×(3-1)×(3-2).
Confused? Let me explain why it works.
There are 3 possibilities for the first stamp: A, B, or C.
There are 2 possibilities for the second space: The two stamps that are not in the first space.
There is 1 possibility for the third space: the stamp not used in the first or second space.
So the number of possibilities, in this case, is 3×2×1.
We can see that the number of ways that 3 stamps can be attached is the same regardless of method used.
Just simply divide then multiply by 100
1/6= 0.166667×100=<span>16.6667%
So </span>16.6667% is the answer
if you want it rounded 16.7%
