The line ran _______ the page, right through the centre, and divided the page into two.

Kind : ________ :: Often : Seldom

(By word meaning)

In how many ways can cells in a 3 × 3 grid be shaded, such that each row and each column have exactly one shaded cell? An example of one valid shading is shown. 

There are 4 red, 5 green, and 6 blue balls inside a box. If 𝑁 number of balls are picked simultaneously, what is the smallest value of 𝑁 that guarantees there will be at least two balls of the same colour?

One cannot see the colour of the balls until they are picked.