Have been looking for a formula to give me a curve similar to the following:-

will post this 5 times untill I can post a link

Solid blue line. Doesn't matter if it doesn't exactly fit, I think I can adjust the functions by trial and error once I get it into xls. I am after the y value by inputting the x value, the important bit being the the curve rises steeply, tails off but never starts to go back down as would a quadratic equation ( y=ax2+bx+c ) If someone has something it would be great, have been looking for what seems like ages, many thanks in advance

Paul M

will post this 5 times untill I can post a link

Solid blue line. Doesn't matter if it doesn't exactly fit, I think I can adjust the functions by trial and error once I get it into xls. I am after the y value by inputting the x value, the important bit being the the curve rises steeply, tails off but never starts to go back down as would a quadratic equation ( y=ax2+bx+c ) If someone has something it would be great, have been looking for what seems like ages, many thanks in advance

Paul M