You'll find it easier to understand if you illustrate the problem as what is shown in the attached picture. From the illustration and the problem description, two equations can be formulated:
HJ = 2JK
HJ + JK = HK
2JK + JK = 78
3JK = 78
JK = 78/3
JK = 26
Answer:
1.95secs
Step-by-step explanation:
Given the height of the float expressed as h(t) = -16t2 - 3t + 55.
The floats reach the swimmer at h(t) = 0
Substitute
0 = -16t^2 - 3t + 55.
16t^2 + 3t - 55 = 0
Using the general formula;
t = -3±√3²-4(16)(-55)/2(16)
t = 3±√9+3520/32
t = 3±√3529/32
t = 3+59.41/32
t = 62.41/32
t = 1.95
Hence it will take 1.95secs
The volume formula of a cone is

the r is the radius and h is the height. However, if you multiply by pi, you will get an approximated volume of the cone. So we will multiply like this for now.

Don't worry, we'll use pi in the end.
I'm going to assume that 7 inches is your radius. We need to plug in 7 for r and 4 in for h into the equation. Once we do that, it will look like this.


means we will need to divide one by 3. That gives us 0.33333... now we have to multiply by

we get 16.33333... now the last thing we need to do is multiply by 4, which is h. We get 65.33333. Add pi and you have your answer.
By the binomial theorem,

Each term containing a factor 6 is divisible by 3, since 3 divides 6. The remaining 1 and 2 sum to 3, which is also divisible by 3.