Finance/Math help. I'm not looking for just the answers(know those already), I need to learn how to solve it.

If a treasury bill, maturing in 90 days, can be purchased today at $98,750; assume security is held until maturity and that the investor will receive $100,000(face amount) at that time, determine the holding period return on this investment (Ans .5025%)

J's Supplies Inc had a return on equity of 22% in 2006. Company's net profit margin was 12% and its equity multiplier was 1.7 times. Calculate company's total asset turnover ratio (Ans: 9%)

Jack has saved $50,000 for his son's college. He will start college a year from now. If Jack decides to place the money into a bank certificate of deposit(CD), which bank should be choose? Bank A offers a 1 yr CD carrying an annual 4% rate with interest compounded quarterly while Bank B offers 1 yr CD carrying annual stated interest rate of 3.75% with interest compounded monthly. (ans: A: 9,766, B: 10,000)

I need to learn how to solve them, so any help would be great. Thanks :)

Problem 1:

HPR = ((Present Value, or face Value, End-Of-Period Value) + (Any Intermediate Gains, eg. Dividends or interest the security pays) - (Initial Value)) /(Initial Value)

Since treasury bills do not pay interest, you do not have capital gains, therefore your HPR = (100,000-98,750)/98,750 = 1.265823%, say 1.267%.

While the annualized HPR = ((Face value 鈥?Purchasing Price)/Purchaising price +1)^(360/90) -1 ==(((100000-98750)/98750)+1)^(360/90)-1 =0.0516024 = 5.16024%

Problem 2:

The asset turnover formula is: Asset Turnover = Revenue / Total assets
From the Net Profit Margin, you can obtain Revenues:
Net Profit Margin = Net Profit After Taxes / Revenue = 12% => Revenue = Net Profit After Taxes/12%

Equity Multiplier = Total Assets / Shareholder鈥檚 Equity = 1.7 =>
Total Assets = 1.7* Shareholder鈥檚 Equity

ROE = Net Profit After Taxes / Stockholders' Equity = 22% = > Stockholders' Equity = Net Profit After Taxes/22%

Asset Turnover = Revenue / Total assets = (Net Profit After Taxes/12%)/(1.7* Net Profit After Taxes/22%)
Net Profit after taxes reduces from the numerator and denominator and the formula remains:
Asset Turnover = (1/12%)/(1.7/22%) = 1.078431

Problem 3:
In each of the cases, after 1 year you will have :
FV = PV/(1+r)^n

Bank A: annual 4% interest rate, compunded quarterly, therefore you will have a number of n=4 periods, each period with a 4%/n = 1% interest,
Bank B: annual 3.75% interest rate, compunded monthly, therefore you will have a number of n=12 periods, each period with a 3.75%/n = 0.3125% interest
Future value Bank A = 50,000/(1+1%)/4 = 52,030.2
Future value Bank B = 50,000/(1+0.3125%)/12 = 51,907.56

Take bank A, it pays more than bank B.