Answer:
s = 3.238√f
Step-by-step explanation:
The only way this question can be solved is in terms of r because its value is not given.
Given that
s = 3.87√rf
f = 0.7
Required
Find s
Substitute 0.7 for f
s = 3.87 * √(0.7 * f)
Split square root
s = 3.87 * √0.7 * √f
s = 3.87 * 0.837 * √f
s = 3.238√f
This is as far as it can be solved.
Substitute whatever the value of f is, to get your complete answer
