Ajit scores72, 42 and 66 marks in Physics, Chemistry and Biology. If Mathematics is also taken into account, his average .score increases by 5 marks. What was Ajit’s score in Mathematics ?

Options

A. 80
B. 85
C. 84
D. 74

Answer

To find Ajit's score in Mathematics, we can follow these steps:

### Step 1: Calculate the total marks in Physics, Chemistry, and Biology
Ajit scores:
- Physics: 72
- Chemistry: 42
- Biology: 66

Total marks in Physics, Chemistry, and Biology = 72 + 42 + 66

**Calculation:**
Total = 72 + 42 + 66 = 180

### Step 2: Calculate the average score in Physics, Chemistry, and Biology
The average score can be calculated by dividing the total marks by the number of subjects.

**Calculation:**
Average = Total marks / Number of subjects = 180 / 3 = 60

### Step 3: Determine the new average after including Mathematics
According to the problem, including Mathematics increases the average score by 5 marks.

New average = Old average + Increase = 60 + 5 = 65

### Step 4: Calculate the total marks needed for the new average
Now, we need to find the total marks required to achieve this new average with the addition of Mathematics.

Since there are now 4 subjects (Physics, Chemistry, Biology, and Mathematics), we can find the total marks required for an average of 65.

**Calculation:**
Total marks required = New average × Number of subjects = 65 × 4 = 260

### Step 5: Calculate Ajit's score in Mathematics
Now, we can find Ajit's score in Mathematics by subtracting the total marks in Physics, Chemistry, and Biology from the total marks required.

**Calculation:**
Ajit's score in Mathematics = Total marks required - Total marks in Physics, Chemistry, and Biology
= 260 - 180 = 80

### Conclusion
Ajit's score in Mathematics is **80**.

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