The haemoglobin levels of pregnant females in a community was found to have a mean of 10.6 g/d1, and a standard detion of 2 g/dL. What is the minimum haemoglobin level below which 5% of the pregnant females will have their haemoglobin levels?
7.32
8.64
6.68
8.96
Ans. c. 6.68