# cone concentration

Hello, does anyone know how to work this out when ever I do it I always get o.65% but the answer is 0.6% and idk why? Thank you

The retina of the human eye has an area of approximately 1.094 × 103 mm2
The circular fovea in a human eye has a diameter of 3 × 103 µm
Calculate the area of the fovea as a percentage of the area of the retina.
The area of a circle is πr
2
. Use π = 3.14 in your calculation.
Original post by hgdjhew
Hello, does anyone know how to work this out when ever I do it I always get o.65% but the answer is 0.6% and idk why? Thank you

The retina of the human eye has an area of approximately 1.094 × 103 mm2
The circular fovea in a human eye has a diameter of 3 × 103 µm
Calculate the area of the fovea as a percentage of the area of the retina.
The area of a circle is πr
2
. Use π = 3.14 in your calculation.

Probably because they’ve rounded it off.

I presume you’ve done all the calculations correctly as I have attempted them and got 0.6457…% as an unrounded percentage, which can then be rounded to either 0.6% or 0.65%.

However, because the diameter is given to 1 sf, the answer should be given to the same degree of precision (since it is the least precise piece of information given), hence they gave it as 0.6% rather than 0.65%.
(edited 8 months ago)