A culture of bacteria has an initial population of 15000 bacteria and doubles every 3 hours. Using the formula P= Po. 2, where Pt is the population after t hours, P,
is the initial population, t is the time in hours and d is the doubling time, what is the
population of bacteria in the culture after 20 hours, to the nearest whole number?

256π units²   (answer b)

step-by-step explanation:

the formula for the surface area of a sphere of radius r

is             a = 4πr²

and so, if r = 8 units, then the surface area is:

a = 4π(8 units)² = 256π units²   (answer b)

step-by-step explanation:

there are 36 inches in a yard

25 : 36 = 0.69 yards (you can round to 0.70)

isaiah walks 3 miles due north, turns and then 5 miles due east. how far is he from his starting point?

a^2 + b^2 = c^2

let c = distance from starting point.

(3)^2 + (5)^2 = c^2

9 + 25 = c^2

34 = c^2

sqrt{34} = sqrt{c^2}

sqrt{34} = c