SSC NUMERICAL APTITUDE PREPARATION - PROBABILITY

SSC NUMERICAL APTITUDE PREPARATION 

SUBJECT- PROBABILITY

Question.1:- A bag contains 3 yellow, 2 green and 2 red balls. Two balls are drawn at random. What is the probability that none of the balls drawn is red?

Solution:- Total number of balls = 3 yellow + 2 green + 2 red= 7.

Number of ways of drawing 2 balls out of 7 = 7C2 = 21.

Number of ways of drawing 2 balls out of (3 yellow + 2 green) balls = 5C2 = 10.

Required Probability =  Number of ways of drawing 2 balls out of (3 yellow + 2 green) balls / Number of ways of drawing 2 balls out of 7.

Required Probability = 10/21

Question.2:- In a bag, there are 8 yellow, 7 blue and 6 red balls. One ball is picked up randomly. What is the probability that it is neither yellow nor red?

Solution:- Total number of balls = 8 yellow + 7 blue + 6 red= 21.

Number of ways of drawing 1 ball out of 21 = 21C1 = 21.

Number of ways of drawing 1 ball out of only (7 blue) balls(Neither yellow nor red) = 7C1 = 7.

Required Probability =  Number of ways of drawing 1 ball out of only (7 blue) balls(Neither yellow nor red) / Number of ways of drawing 1 ball out of 21.

Required Probability = 7/21 = 1/3

Question.3:- A bag contains 2 yellow, 1 green and 4 red balls. Two balls are drawn at random. What is the probability that none of the balls drawn is red?

Solution:- Total number of balls = 2 yellow + 1 green + 4 red= 7.

Number of ways of drawing 2 balls out of 7 = 7C2 = 21.

Number of ways of drawing 2 balls out of (2 yellow + 1 green) balls = 3C2 = 3.

Required Probability =  Number of ways of drawing 2 balls out of (2 yellow + 1 green) balls / Number of ways of drawing 2 balls out of 7.

Required Probability = 3/21 = 1/3

SSC ENGLISH LANGUAGE PREPARATION - PREPOSITION

SSC ENGLISH LANGUAGE PREPARATION 

SUBJECT- PREPOSITION

We all know about Preposition like at,in,with etc. A Preposition is a word used before a Noun(Ram, Almora etc) or pronoun(I,he etc) to show its relation with the other words of the sentence.

I am describing some rules to use preposition in our sentence with examples.

1. Between and Among

We use Between for only two persons or things while we use Among for more than two persons and things. 

For Example:-

• Radha distributes books between Ram and Shyam.
• Radha distributes books among Ram, Shyam and Mohan.

2.To and Till

We use To for indicating place while we use Till for indicating time.

For Example:-

• Radha went to the temple.
• Krishna walked till 7 am.

2.At and In

We use At for small towns and villages while we use In for big cities and countries. 

For Example:-

• Krishna lives at mohanpur.
• Radha lives in Nainital.
• Krishna lives at ranikhet in Almora.

2.On And Upon

We use On for stable things which show touch with these things while we use Upon for movable things. 

For Example:-

• The book of Krishna is on the desk.
• The dog jumped upon the table.