Week 15 spam mail quiz question


In week 15 quiz question about spam mails. We know that out of 10000 mails 4500 are spam.
Also we know that 1434 SPAM mails have congratulations as word in it.

Now given mail is spam to find probability of that mail containing congratulations can be directly done using

But in solution whole different way is used.

Can someone help where my thinking is going wrong?

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Hi @mehtavatsald02,
Note that 1434 is the number of emails which have the word congratulations out of the total 1000 mails, not just the 4500 Spam ones.

Hi @Ishvinder,

Here it is written that 1434 SPAM mails have word congratulations.

Yes, but that’s a totally different statement. It doesn’t have any link saying these 1434 are out of 4500.
Please also consider the next line.

Will anyway make the statement more clearly saying 1434 is out of all 1000. For the sake of better understanding of question.

ok that would be helpful
And 1434 spam mails containing “congratulations” out of 10000 mails right?

Hey, I’m so sorry for the confusion occured.
Yes you were right, and the answer can simply be computed as 1434/4500.

The answer in both the cases will also be the same, the minor difference is there from our end as 0.9335 is mistakenly written as 0.9355

1434 is indeed the number of emails containing the word out of 4500.

Sorry once again for the confusion.

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Thanks for confirmation @Ishvinder