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Statistics- probability

please help with this question

A new housing development contains 100 properties of which 40 are semi-detached houses, 25 are detached houses, 20 are semi-detached bungalows and 15 are detached bungalows. a property is selected at random. Determine the probability that the property selected is:

a. either detached or a bungalow or both
i could do it if it were detached or a bungalow but 'or both' is confusing me.

thanks
Reply 1
Avatar for M_E_X
M_E_X
14
Original post by Flint_09
please help with this question

A new housing development contains 100 properties of which 40 are semi-detached houses, 25 are detached houses, 20 are semi-detached bungalows and 15 are detached bungalows. a property is selected at random. Determine the probability that the property selected is:

a. either detached or a bungalow or both
i could do it if it were detached or a bungalow but 'or both' is confusing me.

thanks


contains 100 properties of which 40 are semi-detached houses, 25 are detached houses, 20 are semi-detached bungalows and 15 are detached bungalows

e: misread the question - don't do this! :frown: See below for proper solution.
(edited 13 years ago)
Reply 2
Avatar for v-zero
v-zero
14
It means either a detached house, a bungalow, or a detached bungalow. It isn't a well written question.

Be careful not to count detached bungalows twice.
Reply 3
Avatar for Flint_09
Flint_09
OP
8
Original post by M_E_X


contains 100 properties of which 40 are semi-detached houses, 25 are detached houses, 20 are semi-detached bungalows and 15 are detached bungalows


Ok, so we have:

40 semi-detached houses
25 detached houses
20 semi-detached bungalows
15 detached bungalows

The two in bold are relevant to our question. Obviously a house cannot be both a detached and semi-detached, so the number of houses which are both is zero, and we can ignore it.

Can you finish the problem from here? Hope I've helped!


i couldn't, sorry. it is not giving me the answer in the book, 0.60.
Reply 4
Avatar for M_E_X
M_E_X
14
Original post by Flint_09
i couldn't, sorry. it is not giving me the answer in the book, 0.60.

EEP I misread the question - oops!

"either detached or a bungalow or both"



40 semi-detached houses
25 detached houses
20 semi-detached bungalows
15 detached bungalows

That's better. It's either a detached house, detached bungalow, or semi-detached bungalow.

Get it now? The question tricked me :frown:
Reply 5
Avatar for Flint_09
Flint_09
OP
8
Original post by M_E_X
EEP I misread the question - oops!

"either detached or a bungalow or both"



40 semi-detached houses
25 detached houses
20 semi-detached bungalows
15 detached bungalows

That's better. It's either a detached house, detached bungalow, or semi-detached bungalow.

Get it now? The question tricked me :frown:


thanks alot mate. you made it crystal clear now.

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