Answers

1. 64 is the number of bit strings that are of length 7 having at least four 1s. This can be obtained by finding each of the required combination and adding them.  

   Find the number of required bit strings:

   • Bit: Bit is a digit which is either zero or one.    

   • Bit string: Bit string is a string of bits. A bit string is a string that contains 0 and 1 only.

   • Byte: Byte is a string of 8 bits.  

   If length of the string is n, then there are 2ⁿ bit stings of length n.

   We apply combination formula for this,

                   ⇒    ⁿCr = n!/(n-r)!r!                        

   At least four 1s is 4, 5, 6, 7,  

   ⇒ ⁷C₄ + ⁷C₅ + ⁷C₆ + ⁷C₇ = 35 + 21 + 7 + 1

   ⇒ ⁷C₄ + ⁷C₅ + ⁷C₆ + ⁷C₇ = 64

   Hence 64 is the number of bit strings that are of length 7 having at least four 1s.      

                                

    

   Learn more about bit string here:

   brainly.com/question/14229889

   #SPJ4  

   Reply