Question

Question 1.3 (F/CI) You are assigned to communicate with a truly ancient computer. You must do this by telephone by shouting binary digits over the line, in clumps of seven digits. a) How many different seven-digit binary strings are there to shout? b) For each string (of seven digits) that is shouted, how many digits must be a 1? c) For each string (of seven digits) that is shouted, how many digits must match?

Answer 1

a)

Since it is a binary system, Available Digitis: {0,1}

For seven digits, First digit must be 1, rest 6 digits can be either 0 or 1.

Hence Possible Combinations = 1 * 2*2*2*2*2*2 = 2⁶ = 64

b)

For each string, there must be first digit as 1.

c)

4 digits must match

1000000

1100000

1110000

1111000