Question

There are 70 teachers in a school. Of the 38 male teachers, 8 teach Maths It is known that 2/7 of all teachers teach Maths. Find the probability that a teacher selected at random is.
(a) a male teacher or a teacher who teaches Maths.
(b) a female teacher or a teacher who teaches Maths.
(c) a female teacher or a teacher who does not teach Maths.

@ganeshie8

Answer 1

2/7 of 70 gives 20 that means ...20 maths teachers ..

Answer 2

yup

Answer 3

8 are male maths teacher
and 12 are female maths teacher

Answer 4

oh yes.

Answer 5

then for part a ..what will u do ?
p(E)=favourable /total outcomes

Answer 6

8/38 + 20/70 ???

Answer 7

no ...first is a male teacher ...38/70 and then a teacher who teaches maths will be 2/7 ...sum of these two probabilitites by 2

Answer 8

by 2 because at random also we should get either a male teacher or a teacher who teaches maths

Answer 9

addition isn't it?

Answer 10

\[\frac{ 38/70+2/7 }{ 2 }\]

Answer 11

for part b\[\frac{ 32/70+2/7 }{ 2}\]

Answer 12

for part c\[\frac{ 32/70+4/7 }{ 2 }\]

Answer 13

wait, i don't think part a is correct. the answer is 5/7

Answer 14

ohhhh ....yes sorry i went somewhere .wrong in understanding ...!

Answer 15

this is addition law of probability, isn't it?

Answer 16

@ganeshie8

Answer 17

does the question : "a male teacher or a teacher who teaches Maths" means "a male teacher who is not exactly teaches Maths or a teacher who teaches Maths" ?

Answer 18

apply and see if the answer comes 5/7 ..? den interpretation may be right .

Answer 19

interpretation ?