Experts, please solve the following problem.

24. Which of the following irrational numbers is represented by CE on the given number line?
Graphic
(1) $\sqrt{7.4}$
(2) $\sqrt{8.4}-1$
(3) $\sqrt{8.4}+1$
(4) $\sqrt{8.4}$

Dear student,

While drawing the root of numbers on the number line we first draw a line AB of the magnitude of root i.e if we are to find root 5.3 then we must draw first AB =5.3 cm. 
Similarly here AB =8.4 cm hence BE = $\sqrt{8.4}$cm
Now CE =BE- BC
               =$\sqrt{8.4}$-1

Regards