I need help with statistic problem

Aschool district uses a costly interviewrbased test to measure reading comprehension on a scale of O to 100 among its third graders. It randomly selects 20 students for testing and then calculates a 99% condence interval for the thirdgrade population mean score. Select all the true statements below. D About 99% of district third-graders' scores are in the interval. C] If the district were to collect manv random samples of size 20. about 99% of those intervals would contain the district third-grade population mean score. Cl Decreasing the condence level from 99% to 90% and calculating the interval again would yield a narrower intervaL Cl Adding 10 to each student's score would yield a wider interval. CI If the sample mean is not in the center 99% of the distribution of sample means {for n=20), then the interval does not contain the population mean