5000 stars were found in a CCD image. Since the average diameter of the stars on the CCD image is 10 pixels and the standard deviation of the diameters is 4 pixels.

a)What is the number of stars in the range of pixel size 8 to 4?

b)What is the number of stars with pixel size greater than 16?

c)What is the number of stars in the +-1s (standard deviation) range, assuming that the star diameters conform to the normal distribution?

Please send me answer fast.