The average newborn baby weighs 7.7lbs with standard deviation of approximately 0.5lbs. if this is normal distribution then what percentage of babies would be at least 6.7lbs.

We know that the Mean ( or the average ) is 7.7 lbs.The standard deviation :  SD = 0.5 lbs.7.7 - 2 * 0.5 = 7.7 - 1 = 6.7 lbsIt means that 6.7 lbs is The Mean - 2 Standard deviations.According to the bell - shaped curve of Normal distribution:50 % + 34 % + 13.5 % = 97.5 % 97.5 % of babies would be at least 6.7 lbs.