ajit257 wrote:

why are we adding .7..how do I figure out whether it is OR/AND solution to see if it has to be added or multiplied

To figure out whether you need OR/AND, focus on how you speak about it.

You say, "I need a shirt AND a trouser" - AND so multiplication

"I need a shirt OR a T-shirt" - OR so addition

Here you say: It will Rain OR Shine

Rains - probability of party is 15%

Shines - probability of party is 70%

Since it will Rain OR Shine, total probability = 15% + 70% = 85%

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Karishma

Veritas Prep GMAT Instructor

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