He following is a string of ASCII characters whose bit patterns have been converted into hexadecimal for compactness: 4A EF 68 6E 20 C4 EF E5.
Of the 8 bits in each pair of digits, the leftmost is a parity bit. The remaining bits are the ASCII code.

(a) Convert to bit form and decode the ASCII.
(b) determine the parity used: odd or even.

a) Please see below as the answer is self explanatory.

b) odd parity.

Explanation:

As the hexadecimal system, has as its base the decimal 16, which is the 4th power of 2 (base of the binary system), each hexadecimal digit can be expressed of a linear combination of 4 binary digits, as follows:

Hex = b₃*2³ + b₂*2² + b₁*2¹ + b₀*2⁰, where bₙ = 0 or 1.

So, we can convert the hexadecimal bit pattern to binary, as follows:

4A = 01001010

Now, if the leftmost bit is a parity bit, the ASCII code is represented by the 7 rightmost bits:

⇒ ASCII = 1001010 = 74

Repeating the same process for the remaining pairs of hex digits, we have:

EF = 11101111 ⇒ ASCII = 1101111  = 111

68 = 01101000 ⇒ ASCII = 1101000 = 104

20 = 00100000 ⇒ ASCII = 0100000 = 32

C4 = 11000100 ⇒ ASCII = 1000100 = 68

EF = 11101111 ⇒ ASCII = 1101111  = 111

E5 = 11100101 ⇒ ASCII = 1100101 = 101

b) Due to any pair of digits has an odd number of 1s, the parity used is odd parity.