3x - (2x + 8) = -6
3x -2x - 8 = -6
x - 8 = -6
x - 8 + 8 = -6 + 8
x = 2
(2 × (6cm x 9cm)) + (2 × (6cm x 5.1cm)) + (2 × (9cm x 5.1cm)) = 261 square cm
![\bf \textit{surface area of a cylinder}\\\\ SA=2\pi r(h+r)~~ \begin{cases} r=radius\\ h=height\\[-0.5em] \hrulefill\\ r=13.5\\ h=90 \end{cases}\implies SA=2\pi (13.5)(90+13.5) \\\\\\ SA=27\pi (103.5)\implies SA=2794.5\pi \implies SA\approx 8779.18](https://tex.z-dn.net/?f=%5Cbf%20%5Ctextit%7Bsurface%20area%20of%20a%20cylinder%7D%5C%5C%5C%5C%20SA%3D2%5Cpi%20r%28h%2Br%29~~%20%5Cbegin%7Bcases%7D%20r%3Dradius%5C%5C%20h%3Dheight%5C%5C%5B-0.5em%5D%20%5Chrulefill%5C%5C%20r%3D13.5%5C%5C%20h%3D90%20%5Cend%7Bcases%7D%5Cimplies%20SA%3D2%5Cpi%20%2813.5%29%2890%2B13.5%29%20%5C%5C%5C%5C%5C%5C%20SA%3D27%5Cpi%20%28103.5%29%5Cimplies%20SA%3D2794.5%5Cpi%20%5Cimplies%20SA%5Capprox%208779.18)
well, the last part will be with a calculator, but you can simply use the area in π terms.
Answer:
The probability density function for the average length of life of the two components is 
Step-by-step explanation:
Exponential distribution:
The exponential probability distribution, with mean m, is described by the following probability density:

In which
is the decay parameter.
Each missile has a length of life governed by the exponential distribution with mean 1 (with measurements in hundreds of hours). Find the probability density function for the average length of life of the two components.
2, each with mean 1 means that 
So the probability density function is:

The answer is (6/25). I just multiplied the 2 numbers, but I'll explain with something simpler:
Take the number 100, let's say I want (1/10) from that 100,
and from that (1/10), I want (4/5).
Well a tenth of 100 is 10, and four fifths of 10 is 8, thus we have 8/100 as a total (or 4/50)
The same answer can be found when multiplying (1/10) and (4/5), giving us (4/50) or (8/100)