thanks guys, I thought d = r^2, so thats why I was stuck.

I also need help on the second part, ;

from this derive an expression that gives the resolution of the density measurement

in terms of the resolution of the mass and diameter measurements

and

respectively.

my booklet gives me this equation for resolution

I am not even sure what exactly is being asked here, but I did manage to work out

density =

and from the rearranged volume formula

so if I jut plug in v into density formula, than differentiate I get

If this is correct, than can someone please help me with the other part of the equation, deltap/deltaaV

thank you