So, 30 marbles, which 20 red and 10 blue. Take 9 marbles, how mane red left in the jar?

(1) Says that the ratio of red to blue is 2:1 among the 9 taken.

Basically, you took 6 red and 3 blue out of the jar (only possible ratio 2:1 in 9 marbles). Which let´s you calculate the remaining red ones (20-6). SUFF

(2) Of the first 6 marbles removed, 4 are red
Doesn´t gives data about the other 3 taken ones, so now chance of giving an accurate answer on how many red ones remain in the jar. INSUFF

Answer is A

IMO A


Total 9 marbles removed..

Ratio 1:2 so

we can find the no. of red removed.....

Suff


2. next 3 can be anynumber for Red

Insuff