CASE 3. RULE. tion ; double the first figure after the point for shillings, adding one, if the second be 5 or upwards; the second, if less than 5, or its excess above 5, call tens, and the third units of farthings, abating one when above 12, and two if above 36. EXAMPLES. 1 What is the value of .7854166 of a pound ? 27854166 By inspection. 20 ,7854166 answer Zgr. 1,424na. 11 What THE SINGLE RULE OF THREE ÎN DECIMALS. • The operation both in direct and inverse proportions are agreeably to those rules in pages 59 and 63, having regard to placing the points. .. DIRECT PROPORTION. EXAMPLES. 1 If 1,41b. of mace cost 14,5$. what cost 75,311b. : lb. s. lb. £. S. d. gr.' As 1,4 : 14,5 :: 75,31 : 38 19 11 3.52 answer. 18 What must be paid for 7 yards of broad cloth, at 5.1 dollars per yard ? answer 40,5625 D. or 40D. 561cts. 19 How does broad cloth sell per yard when 7 yards cost 40 D. 561 cents. ? answer 5,5D. * 20 The French foot is just 1,068ft. English ; how tall then would a 6ft. Philadelphian be at Paris answer þut 5,618ft. INVERSE PROPORTION. EXAMPLES 1 How many men can do as much work in ,4 of a month, as 16 could in a month and a half ?. mo. men. mo. men.. · As 1,5 : 16 : 94 ; 60 answer. 2 If, when wheat flour is as high as 61. per C.wt. the half penny cake weighs 1,1333oz, what should be the weight of it, when flour is only 1,8125l. per hundred weight ? oz. oz. dr. answer 3,75=3 12 3. If a board be ,75 foot broad, what length will it require to measure 12 square feet ? answer 16ft...? 4. How much Persian ,75yd. wide will line 25,5 yards of five quarter cloth: "answer 42,5yds. 5 A had 40,7 yards of linen for which В gave him 25,6 ells of Holland, valued at 4,5s. per ell; how'was A's linen rated per yard? .answer 2s. 9d. 3,8gr. . 6 How many dollars of 7,5s. each, should be given in exchange for 100 French guineas, at 34,5s. ? answer 460! 7 What sum has A at interest, when it yields as much in 7 months, as B's 4501. do in 15? answer 9001. The Double RULE OF THREE IN DECIMALS. Questions in this rule are wrought as in whole numbers, placing the points agreeably to the preceding directions. EXAMPLES. 1 If 3 men receive 8,91. for 19,5 days labour; how much must 20 men have for 100,25 days . |