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Lad os lave lidt sandsynlighedsregning med kort.

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I denne video vil vi antage

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at der ingen jokere er.

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Du kan lave samme opgaver med en joker,

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men så er tallene blot lidt anderledes.

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Med det sagt,

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lad os først huske hvor mange kort,

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der er i et sæt spillekort.

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Du har 4 kulører, spar, ruder

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klør og hjerter.

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Du har 4 kulører og i hver af dem

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er der 13 forskellige kort

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eller

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Du har esset, så har du en 2'er, en 3'er, en 4'er

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en 5'er, en 6'er, 7, 8, 9, 10

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og så har du knægt, konge og dame.

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Det er i alt 13 kort.

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For hver kulør har du hver af disse.

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D

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Du kan have en ruder knægt, en klør knægt

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en spar knægt eller en hjert knægt.

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Når du ganger disse,

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Du tager et sæt spillekort og fjerner jokerne,

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og tælle dem, men du kan ogå

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gange de 4 kulører, hver med 13 kort.

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Du har 4 gange 13, som er 52 kort et sæt.s

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s

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Eller du kan sige,

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der er 13 af hver kulør

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og der er 4 kulører

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så igen 13 gange 4 og du får 52 kort.

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Lad os se på sandsynligheden for

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forskellige hændelser.

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Lad os sige jeg blander kortene godt.

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Jeg blander dem rigtig godt

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og så vælger jeg tilfældigt et kort fra bunken.

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Hvad er sandsynligheden for at

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jeg trækker en knægt?

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Hvor mange lige sandsynlige hændelser er der?

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Du kan vælge ethvert af de 52 kort.

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Der er 52 muligheder for at trække et kort.

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Hvor mange af de 52 muligheder er knægte?

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Du har spar knægt, ruder knægt,

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kør knægt og hjerter knægt.

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Der er 4 knægte i et sæt.

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Det er 4/52. Disse kan begge dividiers med 4

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4 divideret med 4 er 1. 52 divideret med 4 er 13.

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Hvad er sandsynligheden.

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Jeg gør det lige igen.

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Jeg putter knægten tilbage.

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blander kortene igen.

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Så jeg igen har 52 kot.

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Hvad er sandsynligheden for at få en hjerter+

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Hvad er sandsynligheden for at jeg tilfældgit

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fra et blandet sæt trækker en hjerter?

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Der er igen 52 mulige kort.

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jeg kan vælge i mellem.

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52 lige sandsynlige muligheder.

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Hvor mange af dem er hjerter?

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13 af dem er hjertere.

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Der er 13 kort i hver kulør.

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så der er 13 hjertere i sættet.

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Der er 13 rudere i sættet.

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Der er 13 sparer i sættet.

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Der er 13 klører i sættet

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13 ud af 52 vil være en hjerter, og begge disse

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kan divideres med 13.

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Det er det samme som 1/4.

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1 ud af 4 gange vil jeg få en hjerter

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eller jeg har en sandsynlighed på 1 ud af for at få en hjerter.

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når jeg tilfældigt vægler et kort fra et blandet sæt.

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Lad os nu gøre det lidt mere spændende.

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eller måske er det lidt indlysende.

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Hvad er sandsynligheden for at jeg vælger

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noget der er en knægt og en hjeter?

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Jer der kender lidt til kort

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ved at der kun er

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et kort, der både en knægt og en hjerter.

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Det er hjerter knægt.

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