if we look on one side, we already have one measurement. 4 cm. ok, that's the measurement on that side. look to the left now. that other side is also the same length, so we take that number and multiply it be 2 to get
Wait! we're not done yet. look at the top. do you see the 3? well that's the width for the top of the rectangle. the bottom must be the same to right? so we get
add both equations and you get
The answer is 14cm! Don't forget to label. ;)
Answer:
Proved
Step-by-step explanation:
From the given parameters, we have:
i.e. the length of each security numbers
i.e. 2 security numbers
Required
In 513 security numbers, 2 must have matching zeros
To do this, we make use of Pigeonhole principle.
First, we calculate the number of all security numbers not having matching zeros.
Each of the 9 digits can be selected in 2 ways.
2 ways implies that each digit is either 0 or not
So, total selection is:
Apply Pigeonhole principle
The principle states that: suppose there are n items in m containers, where , then there is at least one container that contains more than 1 item.
This means that if there are 512 security number without matching zeros, then there is 1 (i.e. 512 + 1) with matching zeros.