September 2018

Permutation Problems - 01

Problem
In how many ways can the letters of the word MATHALINO be arranged if the vowels are to come together?
 

Problem
In how many ways can the letters of the word MATHEMATICS be arranged if the consonants are to come together?
 

Probability

Probability
For outcomes that are equally likely to occur:

$P = \dfrac{\text{Number of favorable outcomes}}{\text{Total number of possible outcomes}}$

 

If the probability of an event to happen is p and the probability for it to fail is q, then

$p + q = 1$

 

Number of Marbles in a Bag Containing Black and White Marbles

Problem
If 2 marbles are removed at random from a bag containing black and white marbles, the chance that they are both white is 1/3. If 3 are removed at random, the chance that they all are white is 1/6. How many black marbles are there?
 

Answer Key

 

Probability Problems Involving Cards

A♥ A♦ A♣ A♠
2♥ 2♦ 2♣ 2♠
3♥ 3♦ 3♣ 3♠
4♥ 4♦ 4♣ 4♠
5♥ 5♦ 5♣ 5♠
6♥ 6♦ 6♣ 6♠
7♥ 7♦ 7♣ 7♠
8♥ 8♦ 8♣ 8♠
9♥ 9♦ 9♣ 9♠
10♥ 10♦ 10♣ 10♠
J♥ J♦ J♣ J♠
Q♥ Q♦ Q♣ Q♠
K♥ K♦ K♣ K♠

 

Poker Hand: Probability that Five Cards are of the Same Suit

Problem
In a 5-card poker hand, what is the probability that all 5 are of the same suit?
 

Problem
A certain businessman, who is always in a hurry, walks up an ongoing escalator at the rate of one step per second. Twenty steps bring him to the top. Next day he goes up at two steps per second, reaching the top in 32 steps. How many steps are there in the escalator?

A.   80 C.   50
B.   60 D.   70

09 - Number of Leaps to Take to Catch the Lead

Problem
A cat takes 4 leaps to a dog's 3; but 2 of the dog's leaps are equivalent to 3 of the cat’s. The cat has a start of 50 leaps. How many leaps must the dog take to catch the cat?
 

Probability: A Family of Five Children

Problem
A family chosen at random has 5 children. What is the probability that...

  1.   all are girls or all are boys?
  2.   there are 3 boys and 2 girls?
  3.   at least 1 is a boy?