Explanation

Six scientists A, B, C, D, E, and F present a paper each at a one-day conference. Three of them will present their papers in the morning session before the lunch break whereas the other three will be presented in the afternoon session. The lectures have to be scheduled in such a way that they comply with the following restrictions.

• B should present his paper immediately before C's presentation; their presentations cannot be separated by the lunch break.
• D must be either the first or the last scientist to present his paper.

Question:

In case F and E are the fifth and sixth presenters respectively then which of the following must be true?

A) B is first in the order of presenters.

B) A is first in the order of presenters.

C) A is third in the order of presenters

D) A is fourth in the order of presenters.

Explanation

Explanation

Let the age of D= x

Mother =2x

After 2 years = x+2

Mother = 2x+2

X+2 +2x+2=49

3x+4=49

3x=49_4

3x=45

x=15

Current age of daughter =15

After two years= 15+2=17

Explanation

Let member be = x 

Increased average = x*5

Given Condition:

x*5=38-18

x= 4

Explanation

Median = 10+12

=22/2

=11

Explanation

Length =5:3

suppose the length and width of the field be 5xm and 3xm respectively

Width =42m

3x=42

 x= 42/3

​ =14

∴length=5x=5×14=70m

Explanation

Explanation

Average speed,=2×x×yx+y=2×100×150100+150=200×150250=120km/hr

Explanation

Let's start by calling the two numbers we are looking for x and y.

x + y = 80

x - y = 20

x - y = 20

x = 20 + y

x + y = 80

20 + y + y = 80

20 + 2y = 80

2y = 60

y = 30

x + y = 80

x + 30 = 80

X = 50

Sum: 50 + 30 = 80

Difference: 50 - 30 = 20

Explanation

let

first number=x

2nd number will be= x+2

3rd number will be =x+4

Condition

x+x+2+x+4=66

3x+6=66

3x=66-6

3x=60

x=60/3=20

first number=20

2nd number=20+2=22

3rd number=20+4=24