Problems based on Normal Distribution
Bank Accounts: You work for the business analytics department of a large commercial bank, and you learn that the balances of small-business accounts are distributed on the log-scale according to a normal distribution. You also learn that lower and upper quartiles of the balances are $500 and $50,000, respectively. In the following sub-problems you will end up inferring in small steps what a 95% range of the bank balances is. (For ease of grading, use the memorized rounded multipliers for normal quantiles, not the more exact values from the tables or calculators.)
a) What are the lower and upper quartiles of log10-balances?
b) What are the mean and sd of the log10-balances?
c) What is a 95% range of the log10-balances?
d) What is a 95% range of the balances in $s? State in English what the two boundaries mean.