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.

Step-by-step explanation:

Since we have given that

Number of cards = 8

Probability of the correctness of the car = $\dfrac{5}{8}$

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 = $\dfrac{1}{2}$

So, Mean would be

$E{x}=np=8\times \dfrac{1}{2}=4$

Hence, Fourth option is correct.