1. This is a "thinking" problem. For every fifth part of the tank that is filled, 1/12th of it is being drained away. In effect, the draining is retarding the filling.
So we have: (The portion of the tank being filled per hour) * (time it takes to fill) = (whole tank filled)
In math terms this equates to: (1/5 - 1/12) * X = 1
So we have: (7/60) * X = 1
I'll let you finish this one......just solve for X......your answer will be in hrs.
2. This is a trig problem. We have a triangle whose opposite side is 12 and whose hypotenuse is 24. To find the incline angle, take the sine inverse of 12/24.
3.If the wife gets 1/2 and the daughter gets 1/8, the son gets what's left = 3/8. Then, 3/8 of the estate is 30000.
Let X be the total amount of the estate.
In math terms, we have............. 3/8 * X = 30000
Again, I'll let you finish this one for yourself.
4. Since it rained 7 days out of 30, the probability it rained on any one day is just......... 7/30.
5. The letters don't matter. The first digit is a non-zero number and the other two digits can be any digit from 0-9 inclusive.
So, the possible numbers are from 100 - 999 inclusive. We have 900 of these......... (999-100+1)
So, the total numbers that are 400 or greater = (999-400+1) = 600
Therefore, the probability that a number is greater than 400 is just 600/900 = 2/3.
Hope that helps......good luck!!