Questions on Algebra: Combinatorics and Permutations answered by real tutors!

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Question 1102983: 10Cr=20C(r+1)
Click here to see answer by math_helper(2461)

Question 1106760: How many days of vacation a person will receive in a year if giving 11/4days a month
Click here to see answer by Boreal(15235)

Question 1106754: If nC2=nC3,calculate the value of 6Cn-1
Click here to see answer by stanbon(75887)

Question 1106805: In how many different ways can 6 persons sit down on 8 chairs in a straight line?
Click here to see answer by ikleyn(52778)

Question 1106808: How many numbers, consisting of 3 digits and less than 300, can be formed from the numbers 1,2,3,4,and 5 if the number is allowed to be repeated in more than one digit?

Click here to see answer by greenestamps(13200)

Question 1106806: If P(n,k)=120. Find the possible values of n and k. How many solutions are there?
Click here to see answer by Edwin McCravy(20054)

Question 1106806: If P(n,k)=120. Find the possible values of n and k. How many solutions are there?
Click here to see answer by greenestamps(13200)

Question 1106991: Can you please teach me about Distinguishable Permutation?
Click here to see answer by ikleyn(52778)

Question 1107058: How many even numbers consisting of three digits can be formed from the numbers 1,2,3,4 and 5 if repetition is allowed?
Click here to see answer by Alan3354(69443)

Question 1107058: How many even numbers consisting of three digits can be formed from the numbers 1,2,3,4 and 5 if repetition is allowed?
Click here to see answer by ikleyn(52778)

Question 1107156: How many numbers, consisting of three digits and less than 300, can be formed from the numbers: 1,2,3,4, and 5 if the number is allowed to be repeated in more than one digit?
Click here to see answer by ikleyn(52778)

Question 1107154: A, B, C, and D are four points on the plane such that any three of them are not on the same straightness. How many straight lines can be drawn between any two of these points?
Click here to see answer by ikleyn(52778)

Question 1107161: There are 4 different mathematics bookd and 5 different science books. In how many ways can the books be arranged on a shelf if
A. There are no restrictions
B. Books of the same subject must be placement together
C. If they must be placed alternately
Click here to see answer by math_helper(2461)

Question 1107210: 8c1
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Question 1107228: Proof that ncr=(n/n-r)(n-1 c r)
Proof that n(n-1 c r) = (r+1) (n c r+1)
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Question 1106802: An employer interviews
7
people for
5
management positions in a company, and
3
of the
7
people are women. If all
7
are qualified, in how many ways can the employer fill the management positions if exactly
2
are women
Click here to see answer by Hope 2018(1)

Question 1107118:
For a segment of a radio show, a disc jockey can play 9

records. If there are 13

records to select from, in how many ways can the program for this segment be arranged?
Click here to see answer by Alan3354(69443)

Question 1107627: For a segment of a radio show, a disc jockey can play 6 records. If there are 9 records to select from, in how many ways can the program for this segment be arranged?
Click here to see answer by addingup(3677)

Question 1107692: How to solve n + 4 - 9 - 5n ?
Combining Like Terms
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Question 1107692: How to solve n + 4 - 9 - 5n ?
Combining Like Terms
Click here to see answer by addingup(3677)

Question 1107949: a firm brings 5000 units of a commodity to the market at a price of Rs. 5/- per unit. If the price falls to Rs. 3.50/- per unit, firm offers only 2000 units for sale. Derive the supply function and draw its graph also.
Click here to see answer by Boreal(15235)

Question 1108090: How Many 6 digit odd numbers can be formed by the digit 1,2,2,4,4,4?
Solve it.
Click here to see answer by greenestamps(13200)

Question 1108155: A bus starts with 6 people and stops at 10 different stops, how many different ways can the 6 people depart if any passenger can depart at any bus stop

Click here to see answer by ikleyn(52778)

Question 1108154: How many 6 digit Even numbers can be formed by using 1,2,2,4,4,4?
Click here to see answer by ikleyn(52778)

Question 1108092: How many algebraic expression can be formed by joining the variable a,b,c,d,e,f with (+) and (-)?
Click here to see answer by Fombitz(32388)

Question 1108281: Serial numbers for a product are to be made using 4 letters followed by 4numbersif the letters are to be taking from the first 6 letters of the alphabet with no repeat as and the numbers are taken from the the digit 0 through 9 with no repeats how many serial numbers can be generated
Click here to see answer by ikleyn(52778)

Question 1108423: three research departments have 8, 6, and 10 members, respectively. each department is to select a delegate and an alternate to represent the department at a conference. in how many ways can this be done?
Click here to see answer by ikleyn(52778)

Question 1108553:
Click here to see answer by Alan3354(69443)

Question 1108885: how many are there for selecting four men and five women from a list of 10 men and 8 women?
Click here to see answer by stanbon(75887)

Question 1108880: how many different ways are there to select 7 questions from a 10 question quiz?
Click here to see answer by addingup(3677)

Question 1108953: How many ways can you choose 8 dvds from 20 and watch them in order?
Click here to see answer by ikleyn(52778)

Question 1109403: Please help! A social security number consist of 9 digits, you know
last 4 digits. What is the probability of getting the correct Social Security number if you randomly select the 5 others digits?
Click here to see answer by Alan3354(69443)

Question 1109477: evaluate the following 19�
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Question 1109615: If a 5-card poker hand is dealt from a well-shuffled deck of 52 cards, how many different hands consist of the following:
Three of a kind?
Click here to see answer by Edwin McCravy(20054)

Question 1109790:
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Question 1109790:
Click here to see answer by AnlytcPhil(1806)

Question 1109789: How many different sequences of the form ccvcv are there where c represents one of the 21 consonants and v represents one of the 5 vowels in the English alphabet? Assume no letter can be repeated in the same word.
-----------
Since the sequence needs to be ccvcv I assume that this requires a permutation (order matters).
I was thinking about (21*20*19)+(5*4)...but I don't feel like this is the right way to go.
Thanks in advance for your help!
Click here to see answer by AnlytcPhil(1806)

Question 1109987: Serial numbers for a product are to be made using 4letters followed by 4
numbers. If the letters are to be taken from the first 7 letters of the alphabet with no repeats and the numbers are taken from the digit 0 through 9
with no repeats, how many serial numbers can be generated
Click here to see answer by Boreal(15235)

Question 1110068: Hello, I need help to solve the problem.
A school dance committee is made up of 3 freshman, 2 sophomores, 3 juniors, and 3 seniors.
How many ways are there to sit the committee in a row at a meeting if the students must sit together by grade?
How many ways are there to sit the committee in a row at a meeting if the freshman,sophomores, and juniors must sit by grade, but the seniors can sit wherever they want?
Click here to see answer by stanbon(75887)

Question 1110134: A 46-member football team needs to select co-captains. How many different pairs are possible?
Click here to see answer by jorel1380(3719)

Question 1110182: If 10 students go hiking in pairs, how many different pairs of students are possible?
Click here to see answer by Theo(13342)

Question 1110201: Prove (n+1)p(r) = (n)p(r) + 4.(n)p(r-1)

Click here to see answer by greenestamps(13200)

Question 1110201: Prove (n+1)p(r) = (n)p(r) + 4.(n)p(r-1)

Click here to see answer by ikleyn(52778)

Older solutions: 1..45, 46..90, 91..135, 136..180, 181..225, 226..270, 271..315, 316..360, 361..405, 406..450, 451..495, 496..540, 541..585, 586..630, 631..675, 676..720, 721..765, 766..810, 811..855, 856..900, 901..945, 946..990, 991..1035, 1036..1080, 1081..1125, 1126..1170, 1171..1215, 1216..1260, 1261..1305, 1306..1350, 1351..1395, 1396..1440, 1441..1485, 1486..1530, 1531..1575, 1576..1620, 1621..1665, 1666..1710, 1711..1755, 1756..1800, 1801..1845, 1846..1890, 1891..1935, 1936..1980, 1981..2025, 2026..2070, 2071..2115, 2116..2160, 2161..2205, 2206..2250, 2251..2295, 2296..2340, 2341..2385, 2386..2430, 2431..2475, 2476..2520, 2521..2565, 2566..2610, 2611..2655, 2656..2700, 2701..2745, 2746..2790, 2791..2835, 2836..2880, 2881..2925, 2926..2970, 2971..3015, 3016..3060, 3061..3105, 3106..3150, 3151..3195, 3196..3240, 3241..3285, 3286..3330, 3331..3375, 3376..3420, 3421..3465, 3466..3510, 3511..3555, 3556..3600, 3601..3645, 3646..3690, 3691..3735, 3736..3780, 3781..3825, 3826..3870, 3871..3915, 3916..3960, 3961..4005, 4006..4050, 4051..4095, 4096..4140, 4141..4185, 4186..4230, 4231..4275, 4276..4320, 4321..4365, 4366..4410, 4411..4455, 4456..4500, 4501..4545, 4546..4590, 4591..4635, 4636..4680, 4681..4725, 4726..4770, 4771..4815, 4816..4860, 4861..4905, 4906..4950, 4951..4995, 4996..5040, 5041..5085, 5086..5130, 5131..5175, 5176..5220, 5221..5265, 5266..5310, 5311..5355, 5356..5400, 5401..5445, 5446..5490, 5491..5535, 5536..5580, 5581..5625, 5626..5670, 5671..5715, 5716..5760, 5761..5805, 5806..5850, 5851..5895, 5896..5940, 5941..5985, 5986..6030, 6031..6075, 6076..6120, 6121..6165, 6166..6210, 6211..6255, 6256..6300, 6301..6345, 6346..6390, 6391..6435, 6436..6480, 6481..6525, 6526..6570, 6571..6615, 6616..6660, 6661..6705, 6706..6750, 6751..6795, 6796..6840, 6841..6885, 6886..6930, 6931..6975, 6976..7020, 7021..7065, 7066..7110, 7111..7155, 7156..7200, 7201..7245, 7246..7290, 7291..7335, 7336..7380, 7381..7425, 7426..7470, 7471..7515, 7516..7560, 7561..7605, 7606..7650, 7651..7695, 7696..7740, 7741..7785, 7786..7830, 7831..7875, 7876..7920, 7921..7965, 7966..8010, 8011..8055, 8056..8100, 8101..8145, 8146..8190, 8191..8235, 8236..8280, 8281..8325, 8326..8370, 8371..8415, 8416..8460, 8461..8505, 8506..8550, 8551..8595, 8596..8640, 8641..8685, 8686..8730, 8731..8775, 8776..8820, 8821..8865, 8866..8910, 8911..8955, 8956..9000, 9001..9045, 9046..9090, 9091..9135, 9136..9180, 9181..9225, 9226..9270, 9271..9315, 9316..9360, 9361..9405, 9406..9450, 9451..9495, 9496..9540, 9541..9585, 9586..9630, 9631..9675, 9676..9720, 9721..9765, 9766..9810, 9811..9855, 9856..9900, 9901..9945, 9946..9990, 9991..10035