Ask Me Help Desk - Basic maths questions?

Hi!
I'd like to know if any of you know the answers to the following questions.
I am not sure, although I have attempted these question. Your help is much appreciated! :D
I know it may be easy for some of you guys, but I'm kind of struggling. Hope u can help! Thanks:)

Question one:
A business analyst estimates that company A has a 80% chance of still being in business in three year's time but that company B has only 50% chance. What is the probability of at least one of the companies still being in business in three year's time. What is the main assumption you have made when carrying out this calculation?

Question 2:
A person invests 50,000 thousand pounds in a fund paying 5.3% per annum. After two years she invests a further 10,000 thousand pound. How much will be in the fund after six years?

Question 3:
A sum of money was invested in a risky fund which has increased in value over the last four years by 17%, 13%, -6% and 0% respectively. What is the overall percentage growth in the fund over this period and what is the average annual percentage growth?

Quote:

Question one:
A business analyst estimates that company A has a 80% chance of still being in business in three year's time but that company B has only 50% chance. What is the probability of at least one of the companies still being in business in three year's time. What is the main assumption you have made when carrying out this calculation?

When confronted with an 'at least one' problem, the best thing is to find the probability of none and subtract from 1. What is the prob. A is NOT in business in 3 years? Do the same for B. Multiply those prob. And subtract from 1.

Quote:

Originally Posted by LadyBo

Question 2:
A person invests 50,000 thousand pounds in a fund paying 5.3% per annum. After two years she invests a further 10,000 thousand pound. How much will be in the fund after six years?

Couple of ways you can view it... might want to give 'em both a spin and make sure you get the same answer each time. For one, you've got two investments; one bakes in the oven for 6 years, and the other for 4 years. Obviously, your ending total is the sum of the two.

Any given starting amount A, when growing for n periods at r% per period, will grow to

$A\ \times\ (1+r)^n$ . Be sure to use the decimal form for r in there.

You can use that same formula for the other approach. You have an initial investment growing for two periods, and then a second amount is added. The new amount then grows for another 4 years.