Question

There are four prime numbers written in ascending order of magnitude. the product of the first three is 7429 and of the last three is 12673. find the fourth number?

a. 17

b. 29

c. 23

d. 31

Answer 1

Let the four prime numbers, in the ascending order of magnitude are a, b, c and d.


Given that the product of the first three is 7429 and of the last three is 12673


So a×b×c = 7429


b×c×d = 12673


Divide them:


$\frac{a \times b \times c}{b \times c \times d} = \frac{7429}{12673} \\ \\ \frac{a}{d} = \frac{17}{29}$


Thus the first number is 17

The fourth number is 29

The middle two numbers are 19 and 23.


So your answer is B. 29