If a sample of data has a standard deviation of 3.5, how should this statistic be interpreted? a. The typical difference between an observed value of the variable and the sample mean is 3.5 b. The difference between the highest score and the lowest score in the sample is 3.5 c. The sample of values is very similar to a normal distribution in shape d. Half of the sample of values is less than 3.5 and half the sample is greater than 3.5