Question 1178718
Let's break down this problem to calculate Nina's expected additional allowance.

**1. Define the Outcomes and Probabilities:**

* **Outcome 1:** Grade 90 and above
    * Allowance Increase: Php 50
    * Probability: 12% or 0.12
* **Outcome 2:** Grade 80-89
    * Allowance Increase: Php 20
    * Probability: 45% or 0.45
* **Outcome 3:** Grade 79 and below
    * Allowance Decrease: Php 10 (or -Php 10)
    * Probability: 1 - (0.12 + 0.45) = 1 - 0.57 = 0.43 (or 43%)

**2. Calculate the Expected Value:**

* The expected value (E) is the sum of each outcome multiplied by its probability.
* E = (Outcome 1 * Probability 1) + (Outcome 2 * Probability 2) + (Outcome 3 * Probability 3)
* E = (50 * 0.12) + (20 * 0.45) + (-10 * 0.43)
* E = 6 + 9 - 4.3
* E = 15 - 4.3
* E = 10.7

**3. Interpret the Result:**

* Nina's expected additional allowance for the next grading period is Php 10.70.

**Therefore, Nina's expected additional allowance is Php 10.70.**