947 i thinkkk sugejegdjehrhdhhed
Answer:
17) 750/9 and 18) 364
Step-by-step explanation:
17. Summation of 75*(0.1)^i from i=0 to infinity, that is equal to 75*(Summation of (0.1)^i). Summation of (0.1)^I is a geometric series with a sum of 1/(0.9)=10/9. Hence the series have a sum equal to 75*(10/9)=750/9
18) It's a series with sum=1+3+9+27+81+243=364
Solution: We are given an urn contains 1 red chip and 1 white chip.
Now let's consider the first draw.
The probability of drawing red chip 
We know that if the first chip drawn is red, we will put back that chip into the urn with additional two red chips. So if the first chip drawn is red, we will have 3 red chips and 1 white chip in the urn.
Now if we draw another chip from an urn containing 3 red chips and 1 white chip. Then the probability of drawing a red chip is

Now lets combine these two events
The probability of both are red = P(1st draw is red) . P(2nd draw is red)
=(1/2) x (3/4)
=(3/8)
Therefore, the probability of both selections are red is 3/8
No, not always.
Yes in some cases, like 100 is greater than 0. But -100 is less than zero. So it depends on the number.