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### Question

Average marks of class of 28 students is 51. What will be the average if each student is given 7 as grace marks?

**A**

58.

**B**

59.

**C**

57.

**D**

56.

**Soln.**

**Ans: a**

Let the total score of the class before grace marks be x. Then, by average formula $51 = x/28$, which gives x = $51 × 28 = 1428$. When grace marks = 7 are added for each of the 28 students, the new total becomes $1428 + 28 × 7 = 1624$, the new average becomes $1624/28 = 58$. TIP: As a shortcut, the new average = old average + grace marks.