Question
The sum of the first 10 terms of an arithmetic sequence
is 60 and the 10th term is 5. What is the first term of the sequence?Solution
Sn = (n/2) [2a + (n - 1)d] 60 = 10/2 [2a + (10 - 1)d] 60 = 5 [2a + 9d] 2a + 9d = 12 ------ (i) Given 10th term is 5, so => a10 = a + 9d => a + 9d = 5 ------ (ii) Solving eqn (i) and (ii) we get, => a = 7
612, 487,?, 396, 388, 387
Find the missing number in the given number series.
1, 2, 6, 24, 120, ?What will come in place of the question mark (?) in the following series?
36, 85, ?, 230, 330, 451
Find the missing term in the series:
2, 5, 11, 23, 47, ?
What will come in place of the question mark (?) in the following series?
400, 841, 1202, ?, 1716, 1885
44   45    41   50    ?      59    23
...221, 100, 0, -81, ?
...900 Â Â Â 90Â Â Â 18Â Â Â ? Â Â Â Â 2.16Â Â Â Â 1.08
16, 20, 11, 27, ?, 38
37, 57, 82, ?, 147, 187
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