Math Destroyer Test1 #25

[babytomato]

The question says 50% of a population is vegetarians, 35% ride bicycles, and 20% are both vegetarian and ride bicycles. It asks what the probability that a person chosen at random is either vegetarian or rides a bike. The solution says to subtract 20 from 50 and 35 and add them together. I don't get why you're supposed to add 20 on top of that. Why should you include 20 when you're calculating the probability for either one of them?

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[The Piano Guy]

A Venn diagram will help with this question (check attachment)

either/or = only vegetarian + only rides bike, therefore you have to add 50 and 35 then subtract 20 (20% both) which gives you 65% which is the correct answer.

In Destroyer, he subtracts 20 from each and then adds 20, which imo is confusing but still gives the same answer.

Good luck!

 

[babytomato]

A Venn diagram will help with this question (check attachment)

either/or = only vegetarian + only rides bike, therefore you have to add 50 and 35 then subtract 20 (20% both) which gives you 65% which is the correct answer.

In Destroyer, he subtracts 20 from each and then adds 20, which imo is confusing but still gives the same answer.

Good luck!

Wow, thanks for making the Venn diagram! That makes sense now.