Percentile normal distribution

[SEIFIKAR]

if the random variable X is normally distributed and the values 650 and 850 are at the 60th and 90th percentiles of the distribution of X, respectively. Then which one is greater The value at the 75th percentile of the distribution of X or 750?

 

[Ishuda]

if the random variable X is normally distributed and the values 650 and 850 are at the 60th and 90th percentiles of the distribution of X, respectively. Then which one is greater The value at the 75th percentile of the distribution of X or 750?

What are your thoughts? What have you done so far? Please show us your work even if you feel that it is wrong so we may try to help you. You might also read
http://www.freemathhelp.com/forum/threads/78006-Read-Before-Posting

Hint: You can look up the z value for 60th and 90th percentile. That will give you two equations in two unknowns to compute the mean and standard deviation of the distribution.