Advertisements
Advertisements
Question
Find x in each of the following:
Advertisements
Solution
\[ \frac{1}{4!} + \frac{1}{5!} = \frac{x}{6!}\]
\[ \Rightarrow \frac{1}{4!} + \frac{1}{5(4!)} = \frac{x}{6!}\]
\[ \Rightarrow \frac{5 + 1}{5(4!)} = \frac{x}{6!}\]
\[ \Rightarrow \frac{6}{5!} = \frac{x}{6!}\]
\[ \Rightarrow \frac{6}{5!} = \frac{x}{6 \times 5!}\]
\[ \Rightarrow x = 36\]
APPEARS IN
RELATED QUESTIONS
Evaluate 4! – 3!
Evaluate `(n!)/((n-r)!)`, when n = 9, r = 5
How many 4-digit numbers are there with no digit repeated?
Find r if `""^5P_r = 2^6 P_(r-1)`
Which of the following are true:
(2 +3)! = 2! + 3!
A customer forgets a four-digits code for an Automatic Teller Machine (ATM) in a bank. However, he remembers that this code consists of digits 3, 5, 6 and 9. Find the largest possible number of trials necessary to obtain the correct code.
How many 5-digit telephone numbers can be constructed using the digits 0 to 9. If each number starts with 67 and no digit appears more than once?
Evaluate each of the following:
P(6, 4)
Write the total number of possible outcomes in a throw of 3 dice in which at least one of the dice shows an even number.
Write the number of ways in which 7 men and 7 women can sit on a round table such that no two women sit together ?
The number of five-digit telephone numbers having at least one of their digits repeated is
How many numbers greater than 10 lacs be formed from 2, 3, 0, 3, 4, 2, 3 ?
If the letters of the word KRISNA are arranged in all possible ways and these words are written out as in a dictionary, then the rank of the word KRISNA is
The product of r consecutive positive integers is divisible by
Find x if `1/(6!) + 1/(7!) = x/(8!)`
If (n+2)! = 60[(n–1)!], find n
Find the number of arrangements that can be made out of the letters of the word “ASSASSINATION”.
The total number of 9 digit number which has all different digit is:
The number of ways to arrange the letters of the word “CHEESE”:
A test consists of 10 multiple choice questions. In how many ways can the test be answered if each question has four choices?
How many strings can be formed from the letters of the word ARTICLE, so that vowels occupy the even places?
In how many ways 4 mathematics books, 3 physics books, 2 chemistry books and 1 biology book can be arranged on a shelf so that all books of the same subjects are together
A coin is tossed 8 times, how many different sequences containing six heads and two tails are possible?
Each of the digits 1, 1, 2, 3, 3 and 4 is written on a separate card. The six cards are then laid out in a row to form a 6-digit number. How many of these 6-digit numbers are even?
Each of the digits 1, 1, 2, 3, 3 and 4 is written on a separate card. The six cards are then laid out in a row to form a 6-digit number. How many of these 6-digit numbers are divisible by 4?
If the letters of the word GARDEN are permuted in all possible ways and the strings thus formed are arranged in the dictionary order, then find the ranks of the words
GARDEN
Find the number of strings that can be made using all letters of the word THING. If these words are written as in a dictionary, what will be the 85th string?
Choose the correct alternative:
If `""^(("n" + 5))"P"_(("n" + 1)) = ((11("n" - 1))/2)^(("n" + 3))"P"_"n"`, then the value of n are
The number of arrangements of the letters of the word BANANA in which two N's do not appear adjacently is ______.
In how many ways can 5 children be arranged in a line such that two particular children of them are never together.
If all permutations of the letters of the word AGAIN are arranged in the order as in a dictionary. What is the 49th word?
Find the number of permutations of n different things taken r at a time such that two specific things occur together.
The number of signals that can be sent by 6 flags of different colours taking one or more at a time is ______.
The number of words which can be formed out of the letters of the word ARTICLE, so that vowels occupy the even place is ______.
The number of three-digit even numbers, formed by the digits 0, 1, 3, 4, 6, 7 if the repetition of digits is not allowed, is ______.
If the letters of the word 'MOTHER' be permuted and all the words so formed (with or without meaning) be listed as in a dictionary, then the position of the word 'MOTHER' is ______.
Ten different letters of an alphabet are given. Words with five letters are formed from these given letters. Determine the number of words which have at least one letter repeated.
