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lakkis [162]
3 years ago
9

Andy claims that his bird can do single-digit multiplication. He shows the bird 12 cards with simple multiplication problems tha

t are either correct or incorrect. The bird correctly identifies the correctness of the card 9 times out of 12. If the bird were simply guessing, how many would the bird be expected to get correct? 3 9 6
Mathematics
2 answers:
kondaur [170]3 years ago
8 0

Answer:

The expected number of cards is 6.

Step-by-step explanation:

We know that,

'Expected value = Total number of trials × Probability of each trial'

Let C is the event of correct cards and C' is the event of incorrect cards.

Given,

Total number of cards = 12

Also, the correctness of the card is 9 times out of 12,

Thus, the number of correct cards,

n(C) = 9,

⇒ The number of incorrect cards,

n(C') = 12 - 9 = 3

Also, A card can be can be correct or incorrect,

Thus, The probability of correct card,

P(C)=\frac{1}{2}

And, the probability of incorrect card,

P(C')=\frac{1}{2}

Thus, the expected number of cards = expected number of correct card + expected number of incorrect card

= n(C) × P(C) + n(C') × P(C')

=9\times \frac{1}{2}+3\times \frac{1}{2}

=\frac{9}{2}+\frac{3}{2}

=\frac{12}{2}=6

Ray Of Light [21]3 years ago
6 0
I believe the answer is 6
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