ZgZ AKlTHMEXiC. 



2. What is the present worth of 150I. payable in ^ 

 of a year, discount being at 5 per cent. ? 



Ans. 148I. 2S. ii^d. 



3. Bought a quantity of goods for 150I. ready money, 

 and sold them again for 200I. payable at ~:of a year 

 hence 5 what was the gain in ready money, supposing dis- 

 count to be made at 5 per cent. ? 



Ans. 42h 15s. 5d. 



4. What is the present worth of 120L payable as fol- 

 lows, viz. 50I. at 3 months, 50I. at 5 months, and the rest 

 at 8 months, discount being at 6 per cent. ? 



Ans. 117L 5s. 5-^-d. 



DISCOUNT 



ent payment, according to the principles we have mentioned, is 

 exactly the same as employing the whole sum at interest till the 

 time the debt becomes due arrives ; for if the discount allowed 

 for present payment be put out to interest for that time, its amount 

 will be the same as the interest of the whole debt for the same 

 time : thus, the discount of 105I. due one year hence, reckoning 

 interest at 5 per cent, will be 5I. and 5I. put out to interest at ^ 

 per cent, for one year, will amount to 5I. 5s. which is exactly 

 equal to t;ie interest of 105I. for one year at 5 per cent. 



The truth of the rule for working is evident from the nature of 

 simple interest : for since the debt may be considered as the 

 amount of some principal (called here the present worth) at a 

 certain rate per cent, and for the given time, that amount must be 

 in the same proportion, either to its principal or interest, as the 

 amount of any other sum, at the same rate, and for the same time, 

 is to its principal or interest. 



