Total number of primary outcomes of the random experiment of throwing a balanced coin thrice is n = 2³ = 8.

• Head (H) obtained in all three trials, i.e., outcome HHH is obtained.
• Head (H) obtained in first two trials and Tail (T) obtained, in third trial, i.e., outcome HHT is obtained.
• Head (H) obtained in first trial, Tail (T) obtained in second trial and Head (H) obtained in third trial, i.e., outcome HTH is obtained.
• Tail (T) obtained in first trial and Head (H) obtained in rest of the two trials, i.e., outcome THH is obtained.
• Head (H) obtained in first trial and Tail (T) obtained in rest of the two trials, i.e., outcome HTT is obtained.
• Tail (T) obtained in first trial, Head (H) obtained in second trial and Tail (T) obtained in third trial, i.e., outcome THT is obtained.
• Tail (T) obtained in first two trials and Head (H) obtained in third trial, i.e., outcome TTH is obtained.
• Tail (T) obtained in all three trials, i.e., outcome TTT is obtained.

Hence, the sample space for the random experiment of throwing a balanced coin is expressed as follows:
U = {HHH, HHT, HTH, THH, HTT, THT, TTH, TTT}