The surface area formula for any sphere is 4(pi)(radius)^2
The radius is half of the diameter.
18.6 / 2 = 9.3
So, plug into the formula and solve.
4(3.14)(9.3)^2 = 1086.3 mm^2
Your vertex would be (-1,-5)
and your axis of symmetry is x=-1
A tank with capacity T gallons is empty. Tank will be filled in
minutes
<u>Solution:</u>
Given, A tank with capacity T gallons is empty.
We have to find how many minutes will tank be filled?
Now, Water flows into the tank from pipe X at the rate of X gallons per minute,
And water is pumped out by pipe Y at the rate Y gallons per minute,
Then, together in one minute the amount of water filled will be x – y gallons [as X is greater than Y]
Now, the time take to fill tank = 
Hence tank will be filled in
minutes