3, 6, 21, 28, 55, 66, ?, 120 | vedclass

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Question

(C) Let the given series be $3, 6, 21, 28, 55, 66, x, 120$.Observe the pattern by splitting the series into two alternating sub-series:Sub-series $1$

Vedclass · Accepted Answer

$105$

Vedclass · Answer

(C) Let the given series be $3, 6, 21, 28, 55, 66, x, 120$.Observe the pattern by splitting the series into two alternating sub-series:Sub-series $1$ (odd positions): $3, 21, 55, x$Differences: $21-3 = 18$,$55-21 = 34$,$x-55 = ?$Sub-series $2$ (even positions): $6, 28, 66, 120$Differences: $28-6 = 22$,$66-28 = 38$,$120-66 = 54$Analyzing the second sub-series differences: $22, 38, 54$. These are in an $A.P.$ with a common difference of $16$.Analyzing the first sub-series differences: $18, 34, ?$. These are also in an $A.P.$ with a common difference of $16$.Therefore,the next difference in the first sub-series is $34 + 16 = 50$.Thus,$x = 55 + 50 = 105$.

$4$	$9$	$25$	$103$
$3$	$(a)$	$(b)$	$(c)$

$200$	$184$	$193$	$157$	$182$	$118$	$167$
$150$	$(A)$	$(B)$	$(C)$	$(D)$	$(E)$

$85$	$43$	$44$	$67.5$	$137$	$345$
$125$	$(a)$	$(b)$	$(c)$	$(d)$	$(e)$

$3, 6, 21, 28, 55, 66, ?, 120$

Similar Questions

$4$ $9$ $25$ $103$
$3$ $(a)$ $(b)$ $(c)$

Which of the following numbers will come in place of $(c)$?

$200$ $184$ $193$ $157$ $182$ $118$ $167$
$150$ $(A)$ $(B)$ $(C)$ $(D)$ $(E)$

Which of the following numbers will come in place of $(E)?$

Find the odd number in the given sequence: $2, 4, 4, 16, 8, 256, 64$.

$3, 7, 15, ?, 63, 127$

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