Answer:
22.97
Explanation:
Given that the average cost of an IRS Form 1040 tax filing at Thetis Tax Service is $138.00.
Let x be the average cost an IRS Form 1040 tax filing at Thetis Tax Service
is given
From std normal distribution table we find 77th percentile z value.
z=0.74
Corresponding X value = 155
i.e.
where s is the std deviation
Simplify to get
Std deviation =
