Answer:
•26.376 units
•23.236 units
•34.54 units
•59.66 units
Step-by-step explanation:
The formula for the circumference of a circle is ...
 C = 2πr = πd
 C = 2(3.14)r = 6.28r  or  C = 3.14d
 where r is the radius and d is the diameter.
Put the given radius or diameter into the relevant formula and compute the product. The results are all in "units".
 r = 4.2  ⇒  C = 6.28×4.2 = 26.376
 d = 7.4  ⇒  C = 3.14×7.4 = 23.236
 d = 11  ⇒  C = 3.14×11 = 34.54
 r = 9.5  ⇒  C = 6.28×9.5 = 59.66