 | John Marsh (writing-master.) - 1742 - 238 sider
...12, as 7 is to 28 ; or 3 is to 7, a» i2 is to 28. And when four Numbers.are thus Proportional, then the Product of the Means is equal to the Product of the Extreams. For 12x7=84 the Product of the Means. And 3x28=84 the Product of the Extreams. Wherefore... | |
 | Daniel Fenning - 1802 - 274 sider
...in .if., either continued or interrupted (provided the interruption be between the 2d and 3d term), the product of the means is equal to the product of the extremes. EXAMPLE. Let the 4 numbers be 5, 15, 26, and 78 interrupted; then 5 x 78 = 15 x 26= 390. It will be... | |
 | Isaac Dalby - 1806 - 526 sider
...: b : : g : h (75. Ax. 5.) ac Or thus, since - z= -. • ba and f = > therefore 1=7. hdbh 68. If 4 quantities are proportional, the product of the means is equal to the product of the extremes. Thus suppose a : b : : c : d Then ad = he. For ? = ^ (s+)i and multiplying both fractions by W we have... | |
 | Isaac Dalby - 1807 - 968 sider
...Or thin, since -. =s -. od and f = ^, therefore i ={. * o 6 A . 88. If 4 quantities are proponional, the product of the means is equal to the product of the extremes^ .• Thin suppote a : b : : c : rf . Then ad=.tc. For j = j (^0. and multiplying both freclioni by... | |
 | Zadock Thompson - 1828 - 238 sider
...price, and this must he ohvious from what was said in article 191. 195. Since, in every proportion, the product of the means is equal to the product of the extremes, one of these products may he taken for the other. Now if we divide the product of the means hy one... | |
 | Timothy Walker - 1829 - 156 sider
...proportion. Thus 6 : 9 : : 10 : 15 : : 8 : 12 , is a continued proportion. 63. In every proportion, the product of the means is equal to the product of the extremes. For if two equal fractions be reduced to a common denominator, their numerators must be equal. Thus... | |
 | John Darby (teacher of mathematics.) - 1829 - 212 sider
...are read, a is to b as c to d; therefore -r- = —r 2. When four quantities are proportionals, tha product of the means is equal to the product of the extremes ; that is, if a ; b ; ' c ; d, then will ad = be. Also, if a ; 6 ; rb ; c, then will ac = 62. Whence... | |
 | Oliver A. Shaw - 1832 - 112 sider
...The other principles of the doctrine of proportion may also be demonstrated; as the proposition that the product of the means is equal to the product of the extremes, proportion by alternation, or that if the first term be to the second as the third is to the fourth,... | |
 | Zadock Thompson - 1832 - 186 sider
...product of the first and fourth equals the product of the second and third, or, in other words, that the product of the means is equal to the product of the may stand, 4 : 12 : : 6 : 18, or 18 : 12 : : 6 : 4, or 18 : 6 :": 12 • 4 or 6 : 4 : : 18 : 12, or... | |
 | Francis Joseph Grund - 1833 - 224 sider
...; (because 450 — г is A's gain, and 450 — (500 — x) = — 50 -f- x is B's gain,) and because the product of the means is equal to the product of the extremes, 450,000 — 900 x — 1,000 x -j- 2 x2 = 5 z2 — 250 *. This equation, when reduced, may be written... | |
| |
In any proportion, the product of the means is equal to the product of the extremes. 
