Answer: The smallest possible value of q is 9.
Explanation:
If we have the set of N numbers:
{x₁, x₂, x₃, ..., xₙ}
The mean of this set is:
M = (x₁ + x₂ + x₃ + ... + xₙ)/N
Now, in this case our set is:
{1, 2, 3, 4, 5, 6, p times 5, q times 7}
Then we have a total of:
6 + q + p numbers.
The mean of this set will be:
Mean = 5.3 = (1 + 2 + 3 + 4 + 5 + 6 + p*5 + q*7)/(6 + p + q)
This is the equation that we will use now.
First, we can simplify this as:
5.3 = (21 + p*5 + q*7)/(6 + p + q)
Now we can pass the denominator in the right to the other side as:
5.3*(6 + p + q) = (21 + p*5 + q*7)
31.8 + p*5.3 + q*5.3 = 21 + p*5 + q*7
Now we want to isolate the variable p in one side of the equation.
p*5.3 - p*5 = 21 - 31.8 + q*7 - q*5.3
p*0.3 = q*1.7 - 10.8
p = (q*1.7 - 10.8)/0.3 = q*(1.7/0.3) - 36
p = q*(1.7/0.3) - 36
p = q*(17/10)*(10/3) - 36
p = q*(17/3) - 36
Now we can see that the denominator is 3, so q should be a multiple of 3.
We want to start with the smallest multiples of 3, but if we use q = 3, then we will have a negative value of p (the same happens if we use 1 = 6)
We do not want that, then we need to use q = 9
p = 9*(17/3) - 36
p = 3*17 - 36
p = 15
Then we have;
9 times the number 7
15 times the number 5 (plus one, because it was already on the first 6 numbers that Sam wrote)
The smallest possible value of q is 9.
Now we want to get the smallest possible value of q.
Remember, p and q need to be positive numbers.