Hi everyone,

I think this will be a very basic question for most of you, but I am not the best at maths. I shall provide the question and my attempt at a solution:

Question: "The mean height of 9 female subjects in a room is 167.33 cm. One subject leaves the room. The mean height is now 167.75 cm. What is the height of the female who left the room?"

My attempt:

I figure we could find the change in x (number of subjects) over the change in y (the mean) and then use the answer and subtract it from the original mean:

So: change in x = 9 - 8 = 1

Change in y = 167.75 - 167.33 = 0.42

Thus: 1 / 0.42

Therefore, to find the height of the subject that left we could simply perform the operation: 167.33 - (1/0.42) = 164.5

However, when I submit that answer into the online quiz I am doing, it says the answer is incorrect.

Any help on this issue will be much appreciated! Is my method incorrect?

Thanks,

Ben