Question : Directions: In a college, the total number of students who opted for Biology or Chemistry is 150. Later, 12 students who opted for Biology changed their preference and opted for Chemistry. Now, the number of students in Biology is half the number of students in Chemistry. How many students are in Chemistry now?
Option 1: 88
Option 2: 94
Option 3: 104
Option 4: 100
Correct Answer: 100
Solution : Given: The total number of students = 150 Let the number of students who opted for biology = x and the number of students who opted for chemistry = y This means – x + y = 150 — (i) Now, 12 students who opted for Biology changed their preference and opted for Chemistry. So, the new number of students who opted for biology = x – 12 and the new number of students who opted for chemistry = y + 12
The number of students in Biology is half the number of students in Chemistry – (x – 12) = (y + 12) ÷ 2 2(x – 12) = y + 12 2x – 24 = y + 12 2x – y = 36 — (ii) Adding the equations (i) and (ii) – x + y + 2x – y = 150 + 36 3x = 186 x = 186 ÷ 3 x = 62 Now, put the value of x in the equation (i) – 62 + y = 150 y = 150 – 62 = 88
So, the students who opted for chemistry now are (88 + 12) = 100. Hence, the fourth option is correct.
Application | Eligibility | Dates | Syllabus
Question : Directions: Which of the following numbers will replace the question mark (?) in the given series? 102, 100, ?, 96, 112
Option 1: 98
Option 2: 100
Option 4: 108
Question : Directions: Select the number that will replace the question mark (?) in the following series. 65, 88, 77, 98, 91, 108, ?, 118, 125
Option 1: 104
Option 2: 95
Option 3: 99
Option 4: 107
Question : Select the option that expresses the given sentence in indirect speech. She said to me, "I was thinking of going out for dinner but had changed my mind later on."
Option 1: She said me that she was thinking of going out for dinner but changed her mind later on.
Option 2: She said that she thought of going out for dinner but changed her mind later on.
Option 3: She told me that I was thinking of going out for dinner but changed my mind later on.
Option 4: She told me that she had been thinking of going out for dinner but changed her mind later on.
Question : Directions: The weight of P is twice that of Q. The weight of Q is half that of R. The weight of R is 3 times the weight of T. The weight of T is half that of S. Who is the heaviest?
Option 1: P
Option 2: Q
Option 3: R
Option 4: P or R
Question : Directions: In a class, 80 students study both Computer Science and Electronics. While 100 students study Computer Science. 120 students study Electronics. How many of them study Computer Science only?
Option 1: 100
Option 2: 40
Option 3: 180
Option 4: 20
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile