for a mile long race of boys in secondary school is known to be distrusted normally with a mean of 460 seconds and a standard deviation of 60 seconds. What time separates the shortest 90% of race times from the longest 10 %?
Answer: 536.8
2) The time for a race of school children is known to be distributed normally with a mean of 450 seconds and standard deviation of 50 seconds. Between what two times would the middle 95% of the children run?
Answer: 352, 548
Also, I have a chart for standard normal distribution.
how do I get these answers?