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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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Answer:

a. N=25

b. X[bar]= 60.52

c. Y[bar]= 106.72

d. SSx= 115.24

e. ∑X*∑Y = 4036684

f. SSxy= 202020.3296

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Step-by-step explanation:

Hello!

Using the attached data you need to calculate some statistics.

a) N

The sample size is listed under the first column "subject" You can see that 25 subjects qhere studied so N=25.

b.

The mean of set X is equal to X[bar]= ∑X/n= 1513/25= 60.52

∑X is listed in the second table.

c.

The mean of ser Y is Y[bar]= ∑Y/n= 2668/25= 106.72

∑Y is listed in the second table.

d.

Sum of Squares of set X SSx= ∑X²-[(∑X)²/n]= 91682-[(1513)²/25]= 115.24

e.

∑X*∑Y =1513*2668= 4036684

f.

SSxy= (∑X²-[(∑X)²/n]) * (∑Y²-[(∑Y)²/n])= (91682-[(1513)²/25]) * (286482*[(2668)²/25])= 202020.3296

g.

√(SSx*SSy)= √(115.24*1753)= 449.46

I hope you have a SUPER day!

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Step-by-step explanation:

Given,

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Green marbles = 10,

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Since, here replacement is not allowed,

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=\frac{30}{78}

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Note : The probability of getting a green marble first and a red marble second

= \frac{10}{13}\times \frac{3}{12}

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