How many different arrangements are there of the 11 letters in the word requirement

Distinguishable Ways to Arrange the Word MATHEMATICS
The below step by step work generated by the word permutations calculator shows how to find how many different ways can the letters of the word MATHEMATICS be arranged.

Objective:
Find how many distinguishable ways are there to order the letters in the word MATHEMATICS.Step by step workout:
step 1 Address the formula, input parameters and values to find how many ways are there to order the letters MATHEMATICS.
Formula:
nPr =n!/(n1! n2! . . . nr!)Input parameters and values:
Total number of letters in MATHEMATICS:
n = 11

Distinct subsets:
Subsets : M = 2; A = 2; T = 2; H = 1; E = 1; I = 1; C = 1; S = 1;
Subsets' count:
n1(M) = 2, n2(A) = 2, n3(T) = 2, n4(H) = 1, n5(E) = 1, n6(I) = 1, n7(C) = 1, n8(S) = 1

step 2 Apply the values extracted from the word MATHEMATICS in the (nPr) permutations equation
nPr = 11!/(2! 2! 2! 1! 1! 1! 1! 1! )

= 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x 10 x 11/{(1 x 2) (1 x 2) (1 x 2) (1) (1) (1) (1) (1)}

= 39916800/8

= 4989600
nPr of word MATHEMATICS = 4989600

Hence,
The letters of the word MATHEMATICS can be arranged in 4989600 distinct ways.

Apart from the word MATHEMATICS, you may try different words with various lengths with or without repetition of letters to observe how it affects the nPr word permutation calculation to find how many ways the letters in the given word can be arranged.

Explanation:

For problems, like these, we need to consider the number of total letters and the number of repeated letters.

There are 9 letters in this word, so if all the letters were different there would be #9!# ways of arranging them.

However, we have #3# R's, #2# A's and #2# E's.

So, this expression becomes #(9!)/(3! xx 2! xx 2!) = (362,280)/(6 xx 2 xx 2) = (362,280)/24 = 15,120#.

Hopefully this helps!

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Find the number of different arrangements of the eleven letters in the word "PERSONALITY" if the arrangements are such that S, O and N are separated.

My Solution:

  1. Find total number of ways to arrange 11 letters.
  2. Find number of ways by having S,O and N together.
  3. Use 1 - 2.

$11! - (9 \cdot 8! \cdot 3!)= 37 739 520$

But correct answer is $8! \cdot 9C3 \cdot 3! = 20 321 280$.

May I know what have I done wrong?

asked Feb 28 at 16:19

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I suppose what the problem means by "S, O and N are separated" is that no two of them are adjacent. You've only subtracted out the ones that have these three letters collectively forming a single block. You've yet to exclude the ones with S-O adjacent, S-N adjacent and O-N adjacent.

The answer $8! \cdot 9C3 \cdot 3!$ suggests that such an arrangement that satisfies the requirements can be achieved by first arranging the 8 letters other than S, O and N (there are 8! ways to do so). Then, there are 9 places (the leftmost and rightmost positions, plus 7 gaps in between the 8 letters) among which you choose 3 to place S, O and N. Note that you can only place one of S, O and N in one gap, otherwise you will have two of them adjacent and violating the requirements. After choosing the 3 positions, you can then arrange S, O and N in $3!$ ways. The result then follows by the multiplication principle.

answered Feb 28 at 16:35

How many different arrangements are there of the 11 letters in the word requirement

kairekaire

2128 bronze badges

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CIE May/June 2021 9709 Prob & Stats 1 Paper 53 (pdf)

  • Show Step-by-Step Solutions

  1. The heights in cm of 160 sunflower plants were measured. The results are summarised on the following cumulative frequency curve.
    (a) Use the graph to estimate the number of plants with heights less than 100 cm.
    (b) Use the graph to estimate the 65th percentile of the distribution.
    (c) Use the graph to estimate the interquartile range of the heights of these plants.
  2. The random variable X can take only the values −2, −1, 0, 1, 2. The probability distribution of X is given in the following table.
    Given that P(X ≥ 0) = 3P(X < 0), find the values of p and q. 3 A sports club has a volleyball team and a hockey team. The heights of the 6 members of the volleyball team are summarised by Σx = 1050 and Σx2 = 193 700, where x is the height of a member in cm. The heights of the 11 members of the hockey team are summarised by Σy = 1991 and Σy2 = 366400, where y is the height of a member in cm.
    (a) Find the mean height of all 17 members of the club.
    (b) Find the standard deviation of the heights of all 17 members of the club.
  3. Three fair six-sided dice, each with faces marked 1, 2, 3, 4, 5, 6, are thrown at the same time, repeatedly. For a single throw of the three dice, the score is the sum of the numbers on the top faces.
    (a) Find the probability that the score is 4 on a single throw of the three dice.
    (b) Find the probability that a score of 18 is obtained for the first time on the 5th throw of the three dice.
  1. The lengths of the leaves of a particular type of tree are modelled by a normal distribution. A scientist measures the lengths of a random sample of 500 leaves from this type of tree and finds that 42 are less than 4 cm long and 100 are more than 10 cm long.
    (a) Find estimates for the mean and standard deviation of the lengths of leaves from this type of tree. The lengths, in cm, of the leaves of a different type of tree have the distribution N(μ, σ2). The scientist takes a random sample of 800 leaves from this type of tree.
    (b) Find how many of these leaves the scientist would expect to have lengths, in cm, between μ - 2σ and μ + 2σ.
  2. (a) How many different arrangements are there of the 11 letters in the word REQUIREMENT?
    (b) How many different arrangements are there of the 11 letters in the word REQUIREMENT in which the two Rs are together and the three Es are together?
    (c) How many different arrangements are there of the 11 letters in the word REQUIREMENT in which there are exactly three letters between the two Rs?
    Five of the 11 letters in the word REQUIREMENT are selected.
    (d) How many possible selections contain at least two Es and at least one R?
  3. In the region of Arka, the total number of households in the three villages Reeta, Shan and Teber is 800. Each of the households was asked about the quality of their broadband service. Their responses are summarised in the following table.
    (a) (i) Find the probability that a randomly chosen household is in Shan and has poor broadband service.
    (ii) Find the probability that a randomly chosen household has good broadband service given that the household is in Shan.
    In the whole of Arka there are a large number of households. A survey showed that 35% of households in Arka have no broadband service.
    (b) (i) 10 households in Arka are chosen at random.
    Find the probability that fewer than 3 of these households have no broadband service.
    (ii) 120 households in Arka are chosen at random.
    Use an approximation to find the probability that more than 32 of these households have no broadband service.

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How many different arrangements are there of the 11 letters in the word requirement


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