Question -
Answer -
Given: seven flags areavailable and out of which two are needed to make a signal.
From this, we can say,that we have to select two flags out of seven and arrange these two flags toget one signal.
Seven flags ofdifferent colours are available, so first flag can be selected in 7 ways.
Now, the second flagcan be selected from any one of the remaining flags in 6 ways.
Hence, the requirednumber of signals are 7 × 6 = 42.