Find the sum of the series :–5 + (–8) + (–11) +........ +

Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.
Advertisement

 Multiple Choice QuestionsLong Answer Type

311. The ratio of the sums of and ‘n’ terms of an A .P. is m2 : n2. Show that the ratio of the mth and nth terms is (2m – 1) : (2n – 1).
111 Views

 Multiple Choice QuestionsShort Answer Type

312. The interior angles of a polygon are in A .P. The smallest angle is 120° and the common difference is 5°. Find the number of sides of the polygon. Sol. Let ‘n’ be the sides of the polygon. We know that some of all interior angies of a polygon = (n - 2) x 180 degree.

99 Views

313. Find the sum of the series :

4 + 8 + 12 +......... + 100.

113 Views

314. Find the sum of the series :

7 + 10 1/2 + 14 + .. .. + 84.
109 Views

Advertisement
315. Find the sum of the series :
34 + 32 + 30 +........ + 10
91 Views

Advertisement

316. Find the sum of the series :
–5 + (–8) + (–11) +........ + (–230).


Let ‘a’ be the first term and d the common difference then,
a = - 5,  d = - 3, a= - 230 = l
We know that, a= a + (n - 1) d
rightwards double arrow -230 = - 5 + (n - 1) ( - 3)
rightwards double arrow - 230 = -5 - 3n + 3
rightwards double arrow - 230 = -2 - 3n
rightwards double arrow - 228 = -3n

rightwards double arrow space space straight n space equals space 228 over 3 equals 76

We space know space that comma space straight S subscript straight n equals straight n over 2 left square bracket straight a plus straight l right square bracket
So comma space space space straight S subscript 16 equals 76 over 2 left square bracket negative 5 space plus space left parenthesis negative 230 right parenthesis right square bracket
space space space space space space space space space space space space space equals space 38 space left parenthesis negative 235 right parenthesis space minus 8930.
140 Views

Advertisement
317. Find the sum of all natural numbers between 100 and 1000 which arc multiples of 7.
287 Views

318.

Tanvika purchases every year National Saving Certificates of value exceeding the last year purchases by Rs. 25. After 20 years, he find the total value of certificates purchased by him is Rs. 7250. Find the value of the certificates purchased.

(i) in the first year. (ii) in the 12th year.

116 Views

Advertisement
319. Two motorist A and B starts together in the same direction from New Delhi to Mumbai. A travels with the uniform speed of 100 km/hr and B travels 50 km/hr in the first hour and increases the speed by 5 km/hr. After how many hour will ‘B’ overtake A, if both motorist never stops.
108 Views

320. Nimit saves Rs. 50 during a month, Rs. 100 during next month, Rs. 150 in next month, if he continues his savings in this way, in how many months will he save Rs. 10500.
163 Views

Advertisement