The probability is about 85.29%.
To do this, you need to first find the z-score on each end of the interval. Then, you can subtract the percents to find the percent in the middle.
Lower:
(1000 - 1252) / 129 = -1.18 which gives a probability of 11.9%
Upper:
(1500 - 1252) / 129 = 1.92 which gives a probability of 97.19%
97.19 - 11.9 = 85.29
