(c) 507\(_2\) to Binary system.
(a) Convert \(AB1_{16}\) to the Octal system
Step 1: Write each hexadecimal digit as 4 binary bits.
\[A=1010,\quad B=1011,\quad 1=0001\]
\[AB1_{16}=1010\,1011\,0001_2\]
Step 2: Regroup the binary digits in threes from the right.
\[101\;010\;110\;001\]
Step 3: Convert each group of three to its octal digit.
\[101=5,\;010=2,\;110=6,\;001=1\]
\[\therefore AB1_{16}=5261_8\]
(b) Convert \(1110111.101_2\) to the Denary (base 10) system
Integer part, using place values \(64,32,16,8,4,2,1\):
\[1110111_2=64+32+16+0+4+2+1=119\]
Fractional part, using place values \(\tfrac{1}{2},\tfrac{1}{4},\tfrac{1}{8}\):
\[.101_2=1(0.5)+0(0.25)+1(0.125)=0.625\]
\[\therefore 1110111.101_2=119.625_{10}\]
(c) Convert \(507_8\) to the Binary system
Since the digit 7 is not valid in base 2, the number is in the octal system. Write each octal digit as 3 binary bits.
\[5=101,\quad 0=000,\quad 7=111\]
\[\therefore 507_8=101\,000\,111_2=101000111_2\]
Check by way of denary: \(507_8=5\times8^2+0\times8^1+7\times8^0=320+0+7=327_{10}\), and repeated division of \(327\) by 2 gives \(101000111_2\), confirming the result.