 | Henry Bartlett Maglathlin - 1873 - 362 σελίδες
...half of 84, or of 14 X <i, is the sum of one of the series. Hence, to find the sum of all the terms, Multiply the sum of the extremes by the number of terms, and take half the product. Exercises. 1. The clocks of Venice strike from 1• to 24 ; how many strokes... | |
 | Daniel W. Fish - 1874 - 538 σελίδες
...2. The extremes of an arithmetical progression are 5 and 75, and the number of terms is 15 ; what is the sum of all the terms ? RULE. — Multiply the sum of the extremes by half the number of terms. M FORMULA. — s = sx (a + T). & 3. The extremes are 4 and 40, and the number... | |
 | Philotus Dean - 1874 - 472 σελίδες
...of the extremes by the number of terms, or the sum of the extremes by half the number of terms, or multiply the sum of the extremes by the number of terms and divide the product by 2. EXAMPLES FOR PRACTICE. What is the sum 1. Of 30 terms of 2, 8, 14, etc.? Ans.... | |
 | Horatio Nelson Robinson - 1875 - 462 σελίδες
...equals 80, which is twice the sum of the series ; and 80 -— 2 = 40, the sum of the series. Hence RULE. Multiply the sum of the extremes by the number of terms, and divide the product by 2. EXAMPLES FOR PRACTICE. 1. Find the sum of the series the first term of which... | |
 | Lorenzo Fairbanks - 1875 - 472 σελίδες
...sum of the extremes multiplied by 27 + 3x7 one half the number of terms ; or 5 = 1(^5' ^"*- Hence the RULE. — Multiply the sum of the extremes by the number of terms, and divide the product by 2. 1. The extremes of an arithmetical series are 80 and 4, and the number of... | |
 | Daniel W. Fish - 1876 - 296 σελίδες
...2. The extremes of an arithmetical progression are 5 and 75, and the number of terms is 15 ; what is the sum of all the terms ? RULE. — Multiply the sum of the extremes by half the number of terms. FORMULA. — s = = x (a + I). At 3. The extremes are 4 and 40, and the number... | |
 | Samuel Mecutchen, George Mornton Sayre - 1877 - 200 σελίδες
...equal to 5 times (10 + 2) the sum of the extremes, and the sum of the series is i — '*' ' M = 30. RULE. Multiply the sum of the extremes by the number of terms, and divide the product by two. 2. The first term is 10, the last term 60, and the number of terms 26; what... | |
 | Horatio Nelson Robinson, Daniel W. Fish - 1877 - 374 σελίδες
...equals 80, which is twice the sum of the series. Dividing 80 by 2 gives 40, which is the sum required. RULE. Multiply the sum of the extremes by the number of terms, and divide the product by 2. EXAMPLES FOR PRACTICE. 1. The extremes are 5 and 32, and the number of terms... | |
 | Joseph Ray - 1877 - 402 σελίδες
...the extremes, as there are terms; hence, the sum of the series is 6 times 12 = 72 divided by 2 = 36. Rule. — Multiply the sum of the extremes by the number of terms; and take half the product. 2. The extremes are 2 and 50; the number of terms, 24 : find the sum of the... | |
 | Joseph Ray - 1877 - 350 σελίδες
...extremes, as there are terms; hence, the sum of the series is 6 times 12 = 72 divided by 2 = 36. Bule. — Multiply the sum of the extremes by the number of terms; and take half the product. 2. The extremes are 2 and 50; the number of terms, 24 : find the sum of the... | |
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RULE. Multiply the sum of the extremes by the number of terms, and half the product will be the sum of the terms. EXAMPLES FOR PRACTICE. 2. If the extremes be 5 and 605, and the number of terms 151, what is the sum of the series? 
