Answer:
34 hours
Explanation:
given the figures for the work are
30, 30, 28, and 28
we know that average
A= sum of values/number of values
let the fifth value be x
the number of values is now 5
given that A=30
30=30+30+28+28+x/5
cross multiply
150=116+x
x=150-116
x=34 hours