If people who work at 100% of a program, do the full program in 42 weeks, how many weeks does someone who works at 60% capacity need? 
If people who work at 100% of a program, do the full program in 42 weeks, how many weeks does someone who works at 60% capacity need?

I said 75.6 weeks and here's how I got it:


*

*people who work at 100% do 42 weeks

*people who work at 50% capacity do 84 weeks (double it)

*halfway between 50 and 100 is 75% and halfway between 42 and 84 is 63, so people who work at 75% capacity do 63 weeks

*halfway between 50% and 75% is 62.5% and halfway between 84 weeks and 63 weeks is 73.5 weeks, so people who work at 62.5% capacity do 73.5 weeks

*Someone who works at 60% capacity does 75.6 weeks (or round up to 76 weeks)


Everyone else I asked is giving an answer of 70 weeks (they are doing 42 divided by 0.6). 
I feel like I am right and they are using the wrong equation. Can you either tell me the equation that will give me my answer (and vindicate me) or call me an idiot and I will accept that, please?

My friend, you yourself have stated that one working at 50% needs 84 weeks. (You got this by multiplying 100/50 and 42)
So similarly, one working at 60% needs 42*(10/6)=70 weeks.
Also, one working at 75% needs 42*(100/75)= 56 weeks; you make the mistake here itself, hence your calculations for 60% are wrong.
