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Category: Permutation and Combination

How-many-words-can-be-formed-from-different-letters-of-the-Your-answer-is-wrong-with-not-repeating-So-that-they-shouldn-t-start-with-o-neither-w-and-shouldn-t-end-with-w-and-should-be-r-

Question Number 181971 by Acem last updated on 03/Dec/22 $${How}\:{many}\:{words}\:{can}\:{be}\:{formed}\:{from}\:{different} \\ $$$${letters}\:{of}\:{the}\:“{Your}\:{answer}\:{is}\:{wrong}''\:{with}\:{not} \\ $$$${repeating}?\:{So}\:{that}\:{they}\:{shouldn}'{t}\:{start}\:{with}\:'{o}'\: \\ $$$$\:{neither}\:'{w}'\:{and}\:{shouldn}'{t}\:{end}\:{with}\:'{w}',\:{and} \\ $$$$\:{should}\:{be}'{r}'\:\&\:'{s}'\:{adjacents}. \\ $$$$ \\ $$$$\:\cancel{{O}ya}…{n},\:\cancel{{W}en}…{y},\:{Iog}…\cancel{{w}}\:,\:{You}\cancel{{r}w}\cancel{{s}}…{e}\:\::\:{are}\:{invalid} \\ $$$$\:{Enrsow}…{g}\::\:{is}\:{valid} \\…

If-10-different-balls-are-to-be-placed-in-4-boxes-at-random-then-the-probability-that-two-of-these-boxes-contain-exactly-2-and-3-balls-

Question Number 181939 by greougoury555 last updated on 02/Dec/22 $${If}\:\mathrm{10}\:{different}\:{balls}\:{are}\:{to}\:{be}\:{placed} \\ $$$${in}\:\mathrm{4}\:{boxes}\:{at}\:{random}\:,\:{then}\:{the}\:{probability} \\ $$$${that}\:{two}\:{of}\:{these}\:{boxes}\:{contain} \\ $$$${exactly}\:\mathrm{2}\:{and}\:\mathrm{3}\:{balls}\: \\ $$ Answered by Acem last updated on 02/Dec/22…

The-number-1-2-3-4-7-are-randomly-divided-into-two-non-empty-subsets-The-probability-that-the-sum-of-the-numbers-in-the-two-subsets-being-equal-is-r-s-expressed-in-the-lowest-term-Find-r-s-

Question Number 116397 by john santu last updated on 03/Oct/20 $${The}\:{number}\:\mathrm{1},\mathrm{2},\mathrm{3},\mathrm{4},…,\mathrm{7}\:{are}\:{randomly} \\ $$$${divided}\:{into}\:{two}\:{non}\:−{empty}\:{subsets}. \\ $$$${The}\:{probability}\:{that}\:{the}\:{sum}\:{of}\:{the} \\ $$$${numbers}\:{in}\:{the}\:{two}\:{subsets}\:{being} \\ $$$${equal}\:{is}\:\frac{{r}}{{s}}\:{expressed}\:{in}\:{the}\:{lowest} \\ $$$${term}.\:{Find}\:{r}+{s}\:? \\ $$ Answered by…

A-five-digits-number-divisible-by-3-is-to-be-formed-using-the-number-0-1-2-3-4-and-5-without-repetition-The-total-number-of-ways-this-can-be-done-is-

Question Number 116360 by bemath last updated on 03/Oct/20 $$\mathrm{A}\:\mathrm{five}\:\mathrm{digits}\:\mathrm{number}\:\mathrm{divisible}\:\mathrm{by}\:\mathrm{3} \\ $$$$\mathrm{is}\:\mathrm{to}\:\mathrm{be}\:\mathrm{formed}\:\mathrm{using}\:\mathrm{the}\:\mathrm{number}\: \\ $$$$\mathrm{0},\mathrm{1},\mathrm{2},\mathrm{3},\mathrm{4}\:\mathrm{and}\:\mathrm{5}\:\mathrm{without}\:\mathrm{repetition} \\ $$$$\mathrm{The}\:\mathrm{total}\:\mathrm{number}\:\mathrm{of}\:\mathrm{ways}\:\mathrm{this}\:\mathrm{can} \\ $$$$\mathrm{be}\:\mathrm{done}\:\mathrm{is}\:\_\_ \\ $$ Answered by mr W last…

a-man-goes-in-for-an-examination-in-which-there-are-4-papers-which-maxmum-of-10-marks-for-each-paper-the-no-of-ways-of-getting-20-marks-on-the-whole-is-ans-891-

Question Number 50724 by vajpaithegrate@gmail.com last updated on 19/Dec/18 $$\mathrm{a}\:\mathrm{man}\:\mathrm{goes}\:\mathrm{in}\:\mathrm{for}\:\mathrm{an}\:\mathrm{examination}\:\mathrm{in} \\ $$$$\mathrm{which}\:\mathrm{there}\:\mathrm{are}\:\mathrm{4}\:\mathrm{papers}\:\mathrm{which}\:\mathrm{maxmum} \\ $$$$\mathrm{of}\:\mathrm{10}\:\mathrm{marks}\:\mathrm{for}\:\mathrm{each}\:\mathrm{paper}\:\mathrm{the}\:\mathrm{no}\:\mathrm{of}\:\mathrm{ways} \\ $$$$\mathrm{of}\:\mathrm{getting}\:\mathrm{20}\:\mathrm{marks}\:\mathrm{on}\:\mathrm{the}\:\mathrm{whole}\:\mathrm{is} \\ $$$$\mathrm{ans}:\mathrm{891} \\ $$ Answered by ajfour last updated…

Question-116177

Question Number 116177 by Khalmohmmad last updated on 01/Oct/20 Commented by Dwaipayan Shikari last updated on 01/Oct/20 $$\mathrm{tan}\left(\mathrm{x}−\frac{\pi}{\mathrm{2}}\right)\mathrm{tan}\left(\mathrm{x}+\frac{\pi}{\mathrm{2}}\right)=\mathrm{1} \\ $$$$\mathrm{tan}\left(\mathrm{x}−\frac{\pi}{\mathrm{2}}\right)=\mathrm{cot}\left(\mathrm{x}+\frac{\pi}{\mathrm{2}}\right) \\ $$$$\mathrm{tan}\left(\mathrm{x}−\frac{\pi}{\mathrm{2}}\right)=\mathrm{tan}\left(−\mathrm{x}\right) \\ $$$$\mathrm{x}−\frac{\pi}{\mathrm{2}}=\mathrm{k}\pi+\left(−\mathrm{x}\right) \\…

The-secret-number-is-made-from-the-numbers-1-2-2-3-3-4-5-Many-secret-numbers-can-be-created-if-the-same-number-is-not-adjacent-except-in-the-first-two-place-is-a-1142-b-1212-c-1246-d-

Question Number 115902 by bemath last updated on 29/Sep/20 $${The}\:{secret}\:{number}\:{is}\:{made}\:{from} \\ $$$${the}\:{numbers}\:\mathrm{1},\mathrm{2},\mathrm{2},\mathrm{3},\mathrm{3},\mathrm{4},\mathrm{5}.\: \\ $$$${Many}\:{secret}\:{numbers}\:{can}\:{be}\:{created} \\ $$$${if}\:{the}\:{same}\:{number}\:{is}\:{not}\:{adjacent} \\ $$$${except}\:{in}\:{the}\:{first}\:{two}\:{place}\:{is}\:\_ \\ $$$$\left({a}\right)\mathrm{1142}\:\:\:\:\left({b}\right)\:\mathrm{1212}\:\:\:\:\left({c}\right)\:\mathrm{1246} \\ $$$$\left({d}\right)\:\mathrm{1248}\:\:\:\left({e}\right)\:\mathrm{1250} \\ $$ Terms…

A-delegation-of-4-students-is-to-be-selected-from-a-total-of-12-students-In-how-many-ways-can-the-delegation-be-selected-if-1-2-particular-students-wish-to-be-included-together-only-in-the-delegat

Question Number 50258 by rahul 19 last updated on 15/Dec/18 $${A}\:{delegation}\:{of}\:\mathrm{4}\:{students}\:{is}\:{to}\:{be} \\ $$$${selected}\:{from}\:{a}\:{total}\:{of}\:\mathrm{12}\:{students}. \\ $$$${In}\:{how}\:{many}\:{ways}\:{can}\:{the}\:{delegation} \\ $$$${be}\:{selected}\:{if}: \\ $$$$\left.\mathrm{1}\right)\:\mathrm{2}\:{particular}\:{students}\:{wish}\:{to}\:{be}\: \\ $$$${included}\:{together}\:{only}\:{in}\:{the}\:{delegation}? \\ $$$$\left.\mathrm{2}\right)\:\mathrm{2}\:{particular}\:{students}\:{refuse}\:{to}\:{be}\: \\ $$$${together}\:{and}\:\mathrm{2}\:{other}\:{particular}\:{students}…

There-are-3-teachers-and-6-students-who-will-sit-on-the-9-available-seats-many-arrangements-they-sit-if-each-teacher-is-flanked-by-2-students-

Question Number 115769 by bemath last updated on 28/Sep/20 $${There}\:{are}\:\mathrm{3}\:{teachers}\:{and}\:\mathrm{6}\:{students} \\ $$$${who}\:{will}\:{sit}\:{on}\:{the}\:\mathrm{9}\:{available}\:{seats}.\:{many} \\ $$$${arrangements}\:{they}\:{sit}\:{if}\:{each}\: \\ $$$${teacher}\:{is}\:{flanked}\:{by}\:\mathrm{2}\:{students} \\ $$ Answered by mr W last updated on…