Answer:
62 inches
Step-by-step explanation:
Let x be the height ( in inches ) of Ivan,
∵ Marcia is 5 inches shorter than Ivan,
height of Marcia = x - 5,
Marcia is twice as tall as Sally-Jo,
height of sally-jo = 
Mom is 2 inches taller than Ivan.
⇒ height of mom = x + 2,
Mom is 3 inches shorter than Dad,
height of dad = x + 2 + 3 = x + 5,
So, mean height of family is,



According to the question,
x + 5 = 74 ( 1 ft = 12 in )
x = 69
Hence, mean height of the family = 

= 62 inches