Answer:
a) Robert, Juan, linda
b) Joel
c) Susan, Jan
d) Â Â 165.4
    173.4
    134.5
    156
    147.3 Â
    170.2
   Â
Step-by-step explanation:
The standardized normal distribution  N (0,1)  that expresion stands for normal distribution with mean 0 and standard deviation 1, therefore all positive values are above 0 and all negativa values are below 0
The sample n is 6 then we should use t-student distribution, we calculate t statistic as follow
t = (x-μ)/εε     where standard error is  εε = σ/√6    εε = 9.795  since     σ =24
Robert
0.96 * 9.795  = x - 156         ⇒   x = 165.4
1.78 * 9.795  = x  - 156              x = 173.4
-2.2 * 9.795 Â = x - 156 Â Â Â Â Â Â Â Â Â Â Â Â Â x = 134.5
0 * 9.795 Â Â Â Â = x- 156 Â Â Â Â Â Â Â Â Â Â Â Â Â x= 156
-0.89* 9.795 Â = x -156 Â Â Â Â Â Â Â Â Â Â Â Â Â x = 147.3
1.45 * 0.9795 Â = x -156 Â Â Â Â Â Â Â Â Â Â Â Â x = 170.2