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## Homework Statement

In a bilingual school there is a class of 21 pupils. In this class, 15 of the pupils speak spanish as their first language and 12 of these 15 pupils are Argentine. The other 6 pupils in the class speak english as their first language and 3 of these 6 pupils are argentine.

A pupil is selected at random from the class and is found to be argentine. Find the probability that the pupil speaks spanish as his/her first language.

## Homework Equations

## The Attempt at a Solution

A = speaks spanish as first language

A' = speaks english as first language

B = is Argentine

B' = is English

so P(A|B) =

__(15/21) x (12/15)__= 0.8

(15/21)(12/15) + (6/21)(1/2)

Does this seem right?