Final answer:
By multiplying the number of red counters by the ratio, we find that there are 12 blue counters in the bag.
Step-by-step explanation:
To find out how many blue counters are in the bag, we need to use the given ratio and information. The ratio of red to blue counters is 1:4. This means that for every 1 red counter, there are 4 blue counters. It is also stated that there are 3 red counters in the bag. So, if we use the ratio, we can calculate the number of blue counters by multiplying the number of red counters by the ratio.
Number of blue counters = (Number of red counters) x (Ratio of blue to red counters)
Number of blue counters = 3 x 4 = 12
Therefore, there are 12 blue counters in the bag.