Data Sufficiency

Jeevanantham wrote:Of the companies surveyed about the skills they required in prospective employees, 20 percent required both computer skills and writing skills. What percent of the companies surveyed required neither computer skills nor writing skills?

1) Of those companies surveyed that required computer skills, half required writing skills.
2) 45 percent of the companies surveyed required writing skills but not computer skills.

Please anyone explain this.

Since the problem has given all the data in percentages and the question asked is also about determining a percentage value, let's assume the total number of companies surveyed to be 100.

Could you please explain how you interpreted the first statement..

Correct me if am wrong, " Of those companies surveyed that required computer skills, half required writing skills" -- If those required computer skills is X, then writing skills is 1/2 X .
So according to A + B + neither - Both = Total , X + 1/2X + N + 20 = 100. Is this correct?

Between, you have mentioned 20 = 0.5(X+20) . Please explain this as well.

Jeevanantham wrote:Could you please explain how you interpreted the first statement..

Correct me if am wrong, " Of those companies surveyed that required computer skills, half required writing skills" -- If those required computer skills is X, then writing skills is 1/2 X .
So according to A + B + neither - Both = Total , X + 1/2X + N + 20 = 100. Is this correct?

Between, you have mentioned 20 = 0.5(X+20) . Please explain this as well.

I've chosen 'x' to be the number of companies that required ONLY Computer Skills. If 'x' companies require ONLY computer skills, then (x + 20) companies require Computer Skills (this includes the region common to both Computer and Writing Skills also).

Out of (x + 20) such companies, (20) required Writing Skills. The problem mentions that:
20 is half of (x + 20), or
20 = 1/2 * (x + 20)

Let me go by your variables and let 'X' be the number of people that require Computer skills.
Then,
20 = (1/2)*X

Going by the equation mentioned by you,
100 = CS + WS + N - both
100 = X + Y + N - X/2
100 = 20 + Y + N

This is correct.