 ### SPEED TIME, DISTANCE

A person crosses a 600 m long street in 5 minutes. What is his speed in km per hour? A. 3.6 B. 7.2 C. 8.4 D. 10 Answer: Option B Explanation: Speed = 600/ 5… ### PROBLEMS ON AGES

Father is aged three times more than his son Ali’s. After 8 years, he would be two and a half times of Ali’s age. After further 8 years, how many times would he be of… ### IMPORTANT FORMULAS

Speed, Time and Distance: Speed = (Distance/ Time), Time= (Distance/Speed), Distance = (Speed x Time). Time Speed km/hr to m/sec conversion: x km/hr = x x 5/18 m/sec. m/sec to km/hr conversion: x m/sec =… ### AVERAGE

Important formulas of average Average: Average = (Sum of observations/ Number of observations) Average Speed: Suppose a man covers a certain distance at x kmph and an equal distance at y kmph. Then, the average… ### PROFITS AND LOSS

IMPORTANT FACTS Cost Price: The price, at which an article is purchased, is called its cost price, abbreviated as C.P. Selling Price: The price, at which an article is sold, is called its selling prices,… ### PERCENTAGE

Concept of Percentage: By a certain percent, we mean that many hundredths. Thus, x percent means x hundredths, written as x%. To express x% as a fraction: We have, x% = x/100 Thus, 20% =20/100… ### RATIO AND PROPORTION

Ratio: The ratio of two quantities a and b in the same units, is the fraction a/b and we write it as a : b. In the ratio a : b, we call a as… ### SIMPLE INTEREST

Principal: The money borrowed or lent out for a certain period is called the principal or the sum. Interest: Extra money paid for using other’s money is called interest. Simple Interest (S.I.): If the interest… ### Prepositions in English Grammar

Prepositions A preposition is a word which is used to describe the relationship between other words in a sentence. Prepositions are used before a noun or a pronoun to show its relationship with another word… ### Tenses in English Grammar

Tenses In Grammar, we use ‘Tenses’ to define the time of occurring of the action. The tenses in a sentence show the time of an action or state of being as shown by a verb….