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Quantitative Aptitude

PERMUTATION AND COMBINATION MCQs

Permutations And Combinations

Total Questions : 444 | Page 42 of 45 pages
Question 411. The number of arrangements that can be made with the letters of the word MEADOWS so that the vowels occupy the even places?
  1.    720
  2.    144
  3.    120
  4.    36
 Discuss Question
Answer: Option B. -> 144
THE WORD MEADOWS HAS 7 LETTERS OF WHICH 3 ARE VOWELS.
-V-V-V-
AS THE VOWELS HAVE TO OCCUPY EVEN PLACES, THEY CAN BE ARRANGED IN THE 3 EVEN PLACES IN 3! I.E., 6 WAYS. WHILE THE CONSONANTS CAN BE ARRANGED AMONG THEMSELVES IN THE REMAINING 4 PLACES IN 4! I.E., 24 WAYS.
HENCE THE TOTAL WAYS ARE 24 * 6 = 144.
Question 412. Using all the letters of the word “THURSDAY”, how many different words can be formed?
  1.    8
  2.    8!
  3.    7!
  4.    7
 Discuss Question
Answer: Option B. -> 8!
TOTAL NUMBER OF LETTERS = 8
USING THESE LETTERS THE NUMBER OF 8 LETTERS WORDS FORMED IS ⁸P₈ = 8!.
Question 413. A boy has nine trousers and 12 shirts. In how many different ways can he select a trouser and a shirt?
  1.    21
  2.    12
  3.    9
  4.    108
 Discuss Question
Answer: Option D. -> 108
THE BOY CAN SELECT ONE TROUSER IN NINE WAYS.
THE BOY CAN SELECT ONE SHIRT IN 12 WAYS.
THE NUMBER OF WAYS IN WHICH HE CAN SELECT ONE TROUSER AND ONE SHIRT IS 9 * 12 = 108 WAYS.
Question 414. There are 30 people in a group. If all shake hands with one another , how many handshakes are possible?
  1.    870
  2.    435
  3.    30!
  4.    29! + 1
 Discuss Question
Answer: Option B. -> 435
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 415. In how many different ways can the letters of the word ‘MATHEMATICS’ be arranged so that the vowels always come together?
  1.    10080
  2.    4989600
  3.    120960
  4.    None of these
 Discuss Question
Answer: Option C. -> 120960
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 416. In how many different ways can the letters of the word ‘OPTICAL’ be arranged so that the vowels always come together?
  1.    120
  2.    720
  3.    4320
  4.    2160
 Discuss Question
Answer: Option B. -> 720
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 417. Using all the letters of the word “NOKIA”, how many words can be formed, which begin with N and end with A?
  1.    3
  2.    6
  3.    24
  4.    120
 Discuss Question
Answer: Option B. -> 6
THERE ARE FIVE LETTERS IN THE GIVEN WORD.
CONSIDER 5 BLANKS ….
THE FIRST BLANK AND LAST BLANK MUST BE FILLED WITH N AND A ALL THE REMAINING THREE BLANKS CAN BE FILLED WITH THE REMAINING 3 LETTERS IN 3! WAYS.
THE NUMBER OF WORDS = 3! = 6.
Question 418. How many three letter words are formed using the letters of the word TIME?
  1.    12
  2.    20
  3.    16
  4.    24
 Discuss Question
Answer: Option D. -> 24
THE NUMBER OF LETTERS IN THE GIVEN WORD IS FOUR.
THE NUMBER OF THREE LETTER WORDS THAT CAN BE FORMED USING THESE FOUR LETTERS IS ⁴P₃ = 4 * 3 * 2 = 24.
Question 419. There are two identical red, two identical black, and two identical white balls.In how many different ways can the balls be placed in the cells (Each cell to contain one ball) shown above such that balls of the same colour do not occupy any two consecutive cells?
  1.    15
  2.    18
  3.    24
  4.    30
 Discuss Question
Answer: Option C. -> 24
CASE I : 2 BALLS OF THE SAME COLOUR AND TWO BALLS ARE A DIFFERENT COLOUR ARE ARRANGED.
TWO BALLS OF THE SAME COLOUR AND TWO BALLS OF DIFFERENT COLOURS CAN BE ARRANGED TOGETHER IN WHICH TWO BALLS OF THE SAME COLOUR ARE ADJACENT =4!/2!X2! = 6 WAYS
THEREFORE, TOTAL NUMBER OF ARRANGEMENTS = 6×3 =18 WAYS
CASE II : TWO COLOURS OUT OF 3 CAN BE SELECTED IN = 3C1 = 3WAYS
NOW 2 BALLS OF EACH COLOUR CAN BE ARRANGED ALTERNATIVELY IN 2 WAYS
THUS 4 BALLS CAN BE ARRANGED(TWO OF EACH COLOURS)
= 3×2 = 6WAYS
HENCE TOTAL NUMBER OF ARRANGEMENTS = 18+6 =24 WAYS
Question 420. In how many ways can a group of 5 men and 2 women be made out of a total of 7 men and 3 women?
  1.    63
  2.    90
  3.    126
  4.    45
 Discuss Question
Answer: Option A. -> 63
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

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