A box contains 100 red cards, 200 yellow cards and 50 blue cards.

Total number of cards = 100 + 200 + 50 = 350

∴ Total number of outcomes = 350

(i) Number of blue cards = 50

So, the number of favourable outcomes are 50.

$\therefore P($ drawing a blue card $)=\frac{\text { Favourable number of outcomes }}{\text { Total number of outcomes }}=\frac{50}{350}=\frac{1}{7}$

(ii) Number of cards which are not yellow = 100 + 50 = 150

So, the number of favourable outcomes are 150.

$\therefore P($ drawing a non yellow card) $)=\frac{\text { Favourable number of outcomes }}{\text { Total number of outcomes }}=\frac{150}{350}=\frac{3}{7}$

 
(iii) Number of cards which are neither yellow nor blue = 100

So, the number of favourable outcomes are 100.

$\therefore P($ drawing a card which is neither yellow nor blue $)=\frac{\text { Favourable number of outcomes }}{\text { Total number of outcomes }}=\frac{100}{350}=\frac{2}{7}$