A pipe fills a barrel with vinegar in 20 minutes. A release valve on the barrel, used for drainage, can empty the barrel in 40 minutes. A new employee mistakenly left the drainage valve open as he turned on the pipe to fill a barrel. How long will it take to fill the barrel if the pipe is filling at the same time the valve is emptying?

40 minutes

Step-by-step explanation:

We have a load and a discharge, given by a speed that would be a barrel / minute.

Which means that the loading rate is: 1/20

And the discharge rate: 1/40

Since they are contrary, the result would be the subtraction between these two rates:

1/20 - 1/40 = 1 / x

1 / x = 0.025

x = 1 / 0.025

x = 40

Which means it will take 40 minutes to fill under the mentioned conditions

x = -4

step-by-step explanation:

- 20 - 4(x + 3) = 4x

=> -20 - 4x - 12 = 4x

=> - 32 -4x = 4x

=> -32 = 4x + 4x

=> - 32 = 8x

=> -32/8 = x

=> -4 = x

step-by-step explanation:

i found the life tables for the year 2012. 

life table of males at age 30. probability of dying between ages x and x+1

total population:  

29–30 . . . . . . . . . . . . 0.001030

30–31 . . . . . . . . . . . . 0.001061

males:  

29–30 . . . . . . . . . . . . 0.001420

30–31 . . . . . . . . . . . . 0.001448

white population

29–30 . . . . . . . . . . . . 0.001005

30–31 . . . . . . . . . . . . 0.001037

white males

29–30 . . . . . . . . . . . . 0.001372

30–31 . . . . . . . . . . . . 0.001399

non hispanic white population

29–30 . . . . . . . . . . . . 0.001083

30–31 . . . . . . . . . . . . 0.001116

non hispanic white males

29–30 . . . . . . . . . . . . 0.001477

30–31 . . . . . . . . . . . . 0.001503

jacob, non hispanic white male. 30 years old.

probability that jacob lives to be 30 years old. 

since the given probabilities are probabilities of dying, i think we simply subtract it from 1 to get the probability of living. we will use the probability of non hispanic white male.

                                          probability of living to be 30 y.o.

29 - 30 : 1 - 0.001477 = 0.998523

30 - 31 : 1 - 0.001503 = 0.998497