Which one of the following is the correct order of missing letters in the series given below?
$....sttt...tt...tts....$

Find the missing letters for the given series from the given alternatives:
$c....ac....aa....bc....bcc$

Which number would replace the question mark in the series $2, 7, 14, 23, ?, 47$?

The following question is based on the five three-digit numbers given below:
$519, 368, 437, 246, 175$
Which of the following is the sum of the middle digits of the highest and the lowest numbers?

Choose the correct alternative to complete the series: $....abb....bb....a....bbab....ba$

How many such $4$s are there in the following number series,each of which is immediately followed by $5$ but not immediately preceded by $3$?
$5, 4, 4, 3, 3, 4, 5, 4, 5, 5, 3, 4, 4, 3, 4, 5, 4, 3, 3, 5, 4, 5, 4, 3, 5, 4, 4, 3, 5, 4$