Question

Robert claims that his dog can do single-digit multiplication. He shows the dog 8 cards with simple multiplication problems that are either correct or incorrect. The dog correctly identifies the correctness of the card 5 times out of 8. If the dog were simply guessing, how many would the dog be expected to get correct?

5
8
13
4

Answer 1

Answer: Fourth option is correct.

Explanation:

Since we have given that

Number of cards = 8

Probability of the correctness of the car =
`(5)/(8)`

Since there are two possibilities of the card i.e. correct and incorrect.

Let the number of correct answer that his dog chooses be 'x'.

Since we will apply Binomial theorem:

n = 8

p =
`(1)/(2)`

So, Mean would be

`E{x}=np=8* (1)/(2)=4`

Hence, Fourth option is correct.