At 6 months old, baby tigers usually have a mean mass of 75.1 lbs and follow a normal distribution . An additive was added to the water supply of recently born tigers in hopes they have weights that are larger than the average , by the time they are 6 months old . A small study was conducted with 10 tigers and at 6 months of age, the mean weight was 80.6 lbs with a standard deviation of 6.7 . At the 0.01 significance level , can we conclude that the average weight has increased