How many surveys needed to reach the target percentage?

[excel worker]

EMPLOYEE NAME	SURVEYS	POSITIVE SURVEYS	NEGATIVE SURVEYS	CURRENT PERCENTAGE	TARGET PERCENTAGE	POSITIVE SURVEYS NEEDED
E1	42			50%	75%

If positive surveys vs negative surveys count as 9 positive surveys is equal to or gets canceled by 1 negative survey. With the given data above, how many positive surveys does E1 need to reach the goal of 75% positive survey percentage.

 

[mikerickson]

It sounds like current percentage = Positive/(Positive+9*Negative) which (according to the problem) is .5. Do some algebra and you can get Negative as a function of Positive.
You are looking to find the number of (new) positive surveys such that (Postitive+N)/(Postive+N-9*Negative)=.75
Just plug in the value of Negative from the first calculation and solve for N.

You will see that there is not enough information given to solve the problem. In addition to the current and target percentages, you need the current number of surveys, either Positive surveys, Negative or Total number of surveys will do, but you do need that one more piece of data to make this a solvable problem.