8.5 is 1 away from 7.5, so you are .33 of a standard deviation away from your mean. a normal distribution table gives a value of .1293 for .33, so your probability is 12.93%.

6.5 is also 1 away from 7.5, but now you're talking about everything greater than something below your mean- you'll have more than half the data. So, instead of .1293, you want .8707 (everything else)2. What is the probability that x is greater than 6.5?

Find two probabilities here, then subtract.3. What is the probability that x is greater than 3 but less than 5.5?

In a normal distribution, what percent of data are above the mean?4. What is the probability that x is less than 7.5?