7.69 Determine the value of z* such that

a. 2z* and z* separate the middle 95% of all z values from the most extreme 5% (Hint: See Example 7.26.)

b. 2z* and z* separate the middle 90% of all z values from the most extreme 10%

c. 2z* and z* separate the middle 98% of all z values from the most extreme 2%

d. 2z* and z* separate the middle 92% of all z values from the most extreme 8%