There would be 12 litres in the tub after 4 minutes
6(15) + 10b > = 200
90 + 10b > = 200
10b > = 200 - 90
10b > = 110
b > = 110/10
b > = 11
so she can do 15 days of running plus 11 days of biking....which totals 26 days
Answer: u= ( 4342.08, 5145.92).
Step-by-step explanation: the population mean is estimated using the sample by the formulae assuming a 95% confidence level
u = x' + Zα/2 * (√σ/n) or x' - Zα/2 * (√σ/n)
u = estimated population mean
x' = sample mean = 4744
n = sample size =8
σ = sample standard deviation. = 580
α = level of significance = 1- confidence level = 1-0.95= 0.05
Zα/2 = z score from the normal distribution table for a 2 tailed test = 1.96
First boundary value for interval
u = 4744 + 1.96 ( 580/√8)
u = 4744 + 1.96 * (205.0609)
u = 4744 + 401.92
u = 5145.92
Second boundary value for interval
u = 4744 - 1.96 ( 580/√8)
u = 4744 - 1.96 * (205.0609)
u = 4744 - 401.92
u = 4342.08
Thus the confidence interval for population mean is
u= ( 4342.08, 5145.92).

The surface of interest can be parameterized by

with

and

.
The area of the surface

is given by the surface integral

We have

so the area is given by the double integral