Answer:
The correct option is A:
MAD = 1 + 1/4
Step-by-step explanation:
For a set of N elements {x₁, x₂, ..., xₙ}
The mean is calculated as:
And the mean absolute deviation is calculated as:
Here we have the set of 8 elements:
{ 2, 2, 3, 4, 4, 5, 6, 6}
The mean of this set is:
M = (2 + 2 + 3 + 4 + 4 + 5 + 6 + 6)/8 = 4
Then the mean standard deviation is:
If we simplify this, we get:
MAD = 10/8 = 5/4 = (4 + 1)/4 = 4/4 + 1/4 = 1 + 1/4
MAD = 1 + 1/4
The correct option is A.
Answer:
Hello!!
If the ratio of girls to boys in a class is 3:5, the fraction of the class that are girls is...
Hope this helps!!
First of all, note that all integers are either 0,1, or 2 modulo 3 (if you're not familiar with this terminology, it means that every integer is either a multiple of 3, or it is 1 or 2 away from a multiple of 3).
So, we can think of our numbers as
In order to make sure that the sum of any three adjacent numbers is divisible by 3, we have to make sure that any group of 3 three adjacent numbers contains a 0, a 1 and a 2. This is possible only if we arrange our 9 numbers in 3 groups of 3 numbers containing 0,1 and 2 exactly once, repeating always the same pattern.
For example, we could arrange our numbers following the pattern
or
We have possible patterns. Suppose for example that we choose the pattern
One possible way of following this pattern would be the arrangement
In fact, we substituted every '0' with a multiple of 3 (3, 6 or 9), every '1' with a number 1 away from a multiple of 3 (1, 4 or 7) and every '2' with a number 2 away from a multiple of 3 (2, 5 or 8).
This means that, once we fix a patter, we have 3 choices for the first 3 slots, 2 choices for the next 3 slots, and the final slot will be fixed. So, we have
possible ways of following a fixed pattern. Since the number of patterns was 6, we have
possible arrangements.