Question

Three numbers which are co-prime to each other are such that the product of the first two is $77$ and that of the last two is $143.$ The sum of the three numbers is

• A. $31$
• B. $49$
• C. $23$
• D. $15$

Answer 1

The correct option is A $31$

Since the numbers are co-prime, they contain only $1$ as the common factor.
Also, the given two products have the middle number in common.
So, middle number $=$ H.C.F. of $77$ and $143=11$
Now, the first number $=\frac{77}{11}=7$
and the third number $=\frac{143}{11}=13$
$\therefore$ Required sum $=7+11+13=31$