Final answer:
Approximately 68 percent of the y values lie between one standard deviation below and one standard deviation above the mean.
Step-by-step explanation:
To determine the values between which approximately 68 percent of the y values lie, we can use z-scores. Z-scores measure the number of standard deviations a particular value is from the mean. In a normal distribution, about 68 percent of the values are within one standard deviation of the mean.
Therefore, the values between which approximately 68 percent of the y values lie are one standard deviation below and one standard deviation above the mean. These values can be calculated using the formula:
lower value = mean - standard deviation
upper value = mean + standard deviation
For example, if the mean is 68 and the standard deviation is 2, then the lower value would be 68 - 2 = 66 and the upper value would be 68 + 2 = 70.