Among $P,$ $Q,$ $R,$ $S,$ and $T,$ $S$ is older than $R$ but not as old as $T.$ $Q$ is older than only $P.$ Who among them is the youngest?

In the sequence $5, 1, 4, 7, 3, 9, 8, 5, 7, 2, 6, 3, 1, 5, 8, 6, 3, 8, 5, 2, 2, 4, 3, 4, 9, 6$,how many even numbers are there which are immediately preceded by an odd number and immediately followed by an even number?

How many numbers from $1$ to $100$ are there,each of which is not only exactly divisible by $4$ but also has $4$ as a digit?

$A$ monkey climbs $30$ feet at the beginning of each hour and rests for a while,during which he slips back $20$ feet before he again starts climbing at the beginning of the next hour. If he begins his ascent at $8:00 \, a.m.$,at what time will he first touch a flag at $120$ feet from the ground?

$1.12.91$ is the first Sunday. Which is the fourth Tuesday of December $91$ (in $.91$)?

Akshay is $16^{th}$ from the left end in a row of boys and Vijay is $18^{th}$ from the right end. Avinash is $11^{th}$ from Akshay towards the right end and $3^{rd}$ from Vijay towards the right end. How many boys are there in the row?