Birth weights are normally distributed with a mean of 3419 g and a standard deviation of 494 g. If a hospital plans to set up special attention to the lightest 2% of babies, what weight is used for the cut-off separating the lightest 2% from the others?

Question

anonymous · Answer

2431 g

anonymous · Answer

The region you're concerned about in this particular problem (the lightest ~2% region), is 2 standard deviations to the LEFT of the mean.  We know that 1 standev is 494g.  Simply multiply that number by 2 (988g) and subtract that product from the mean to find out where the cutoff for the lightest ~2% would lay.
3419 g - 988 g = 2431 g.

anonymous · Answer

Don't forget to mark a Best Response.  Thanks.