In an Entrance Examination Ritu scored 56 percent marks, Smita scored 92 percent marks and Rina scored 634 marks . The maximum marks of the examination are 875. What are the average marsk scored by all the three girls together . ?

Options

A. 1929
B. 815
C. 690
D. 643

Explanation

To find the average marks scored by Ritu, Smita, and Rina, we will follow these steps:

### Step 1: Calculate Ritu's Marks
Ritu scored 56% of the maximum marks. The maximum marks are 875.

\[ \text{Ritu's Marks} = \frac{56}{100} \times 875 \]

Calculating this:

\[ \text{Ritu's Marks} = 0.56 \times 875 = 490 \]

### Step 2: Calculate Smita's Marks
Smita scored 92% of the maximum marks.

\[ \text{Smita's Marks} = \frac{92}{100} \times 875 \]

Calculating this:

\[ \text{Smita's Marks} = 0.92 \times 875 = 805 \]

### Step 3: Rina's Marks
Rina's marks are already given as 634.

\[ \text{Rina's Marks} = 634 \]

### Step 4: Calculate Total Marks
Now, we will add the marks obtained by all three girls.

\[ \text{Total Marks} = \text{Ritu's Marks} + \text{Smita's Marks} + \text{Rina's Marks} \]

Substituting the values:

\[ \text{Total Marks} = 490 + 805 + 634 \]

Calculating this:

\[ \text{Total Marks} = 490 + 805 = 1295 \]
\[ \text{Total Marks} = 1295 + 634 = 1929 \]

### Step 5: Calculate Average Marks
To find the average marks, we divide the total marks by the number of girls (which is 3).

\[ \text{Average Marks} = \frac{\text{Total Marks}}{3} \]

Substituting the total marks:

\[ \text{Average Marks} = \frac{1929}{3} \]

Calculating this:

\[ \text{Average Marks} = 643 \]

### Final Answer
The average marks scored by all three girls together is **643**.

---