The probabilites that a student will receive an A,B ,C or D grade are 0.4 , 0.3 ,0.2 and 0.1 respectively . Find the probabilty that a student will receive
Not an A grade .

Options

A. `0.4`
B. `0.6`
C. `0.56`
D. none of these

Answer

To find the probability that a student will not receive an A grade, we can use the concept of complementary probability. Here’s a step-by-step solution:

### Step 1: Identify the probability of receiving an A grade.
The probability of receiving an A grade is given as:
\[ P(A) = 0.4 \]

### Step 2: Use the complementary probability.
The probability of not receiving an A grade can be calculated using the formula:
\[ P(\text{not A}) = 1 - P(A) \]

### Step 3: Substitute the value of \( P(A) \).
Now, substituting the value of \( P(A) \) into the formula:
\[ P(\text{not A}) = 1 - 0.4 \]

### Step 4: Calculate the probability.
Now, perform the subtraction:
\[ P(\text{not A}) = 0.6 \]

### Final Answer:
The probability that a student will not receive an A grade is:
\[ P(\text{not A}) = 0.6 \]

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