Mathematics 2009 JAMB Past Questions - Question 3: Simplify 7 1/12 -4 3/4 +2 1/2

Correct Answer

C

Explanation

7¹∕₁₂ - 4¾ + 2½ 9 -4 1-9+6/12 = 5 ⁷ ‾ ⁹/12 = 19-9/12= 4¹⁰/₁₂ or 4 ⁵/₆ To simplify the expression 7 1/12 - 4 3/4 + 2 1/2, we can start by converting all the mixed numbers to improper fractions. 7 1/12 can be written as (7 * 12 + 1) / 12 = 85 / 124 3/4 can be written as (4 * 4 + 3) / 4 = 19 / 42 1/2 can be written as (2 * 2 + 1) / 2 = 5 / 2Now we can rewrite the expression:85 / 12 - 19 / 4 + 5 / 2To add or subtract fractions, we need a common denominator. In this case, the least common multiple (LCM) of 12, 4, and 2 is 12. Converting all the fractions to have a denominator of 12:(85 * 1) / (12 * 1) - (19 * 3) / (4 * 3) + (5 * 6) / (2 * 6)= 85 / 12 - 57 / 12 + 30 / 12Now that all the fractions have the same denominator, we can combine them:85 / 12 - 57 / 12 + 30 / 12= (85 - 57 + 30) / 12= 58 / 12The fraction 58/12 can be simplified by dividing both the numerator and denominator by their greatest common divisor, which is 2:58 / 12 = (2 * 29) / (2 * 6) = 29 / 6Therefore, the simplified expression is 29/6.