Explanation:

- The average of P1, P2, and P3 is 50. This means:

$$(P1 + P2 + P3)/3 = 50$$

$$P1 + P2 + P3 = 150$$

- P1 is half of the average, which is 50:

$$P1 = 50/2 = 25$$

- Substitute P1 in the sum equation:

$$25 + P2 + P3 = 150$$

$$P2 + P3 = 125$$

- The average of P2 and P3, hence:

$$(P2 + P3)/2 = 125/2 = 62.5$$

- Option:1, 55 - Not correct.

- Option:2, 57.5 - Not correct.

- Option:3, 63.5 - Not correct.

- Option:4, 62.5 - Correct

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