Question

Sam writes on a white board the positive integers from 1 to 6 inclusive, once each, She then writes p

Answer 1

Answer: The smallest possible value of q is 9.

Step-by-step 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.