50
leanne can clean a fish tank in 30 minutes. karl can clean a fish tank in 20 minutes. if they work together, how many minutes does it take them to clean a fish tank?

a)6 minutes
b)10 minutes
c)12 minutes
d)50 minutes

C) 12 minutes

Step-by-step explanation:

Given : Leanne can clean a fish tank in 30 minutes

            Karl can clean a fish tank in 20 minutes

To find :

If they work together, how many minutes does it take them to clean a fish tank.

Solution :

Leanne can clean  fish tank in 30 minutes = 1 fish tank

Leanne can clean fish tank in 1 minute = 1/30 part of fish tank

Karl  can clean  fish tank in 20 minutes = 1 fish tank

Karl  can clean  fish tank in 1 minute = 1/20 part of fish tank

If they work together, they can clean fish tank in 1 minute

=  

=

Thus,  If they work together, they can clean fish tank in 1 minute = 5/60 part of  fish tank

 If they work together, they can clean 5/60 part of fish tank = 1 minute

 If they work together, they can clean 1 fish tank

=

=  

= 12 minutes

Thus , If they work together it will take 12 minutes to clean a fish tank .

so then what are you asking?

step-by-step explanation:

the above table 1 will calculate the population size (n) after a certain length of time (t). all you need to do is plug in the initial population number (no), the growth rate (r) and the length of time (t). the constant (e) is already entered into the equation. it stands for the base of the natural logarithms (approximately 2.71828). growth rate (r) and time (t) must be expressed in the same unit of time, such as years, days, hours or minutes. for humans, population growth rate is based on one year. if a population of people grew from 1000 to 1040 in one year, then the percent increase or annual growth rate is 40/1000 x 100 = 4 percent.

step-by-step explanation: