Sally spelled 2 words incorrectly out of 20 spelling words on the test. What percent grade did Sally get on the test?
1 answer:
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Answer:
Step-by-step explanation:
For each component, there are only two possible outcomes. Either it fails, or it does not. The components are independent. We want to know how many outcomes until r failures. The expected value is given by
In which r is the number of failures we want and p is the probability of a failure.
In this problem, we have that:
r = 1 because we want the first failed unit.
The expected number of systems inspected until the first failed unit is 2.5
Correct option C) 0.98%
<u>Step-by-step explanation:</u>
We know that , there are 2 black ace cards out of 52 cards in a deck & 13 hearts out of 52 cards . Here we have to tell What is the probability of drawing a black ace followed by a heart out of a deck when the cards aren't replaced . Let's find out:
Firstly , a black ace is drawn , so probability :
⇒
Now , A heart is drawn out of 51 cards ( as one black ace is already drawn !):
⇒
So , Probability of occurring both events is :
⇒
⇒
⇒
Percentage = %
Therefore , Correct option C) 0.98%