A 91cm-long wire is cut into two pieces so that one piece length is three-fourth of the other: Find the length of the shorter piece.

Correct option is B

Given:

L = 91 cm

Ratio = 3 : 4

Solution:

Let the lengths of the two pieces be xx x (shorter piece) and y(longer piece). 

then,

x + y = 91   

Substitute x = $$\frac{3}{4}y$$ into x + y =91

$$\frac{3}{4}y$$​ +y = 91

​$$\frac{7}{4}y$$ = 91

y = $$\frac {91\times 4}{7}$$ = 52cm

Now, 

x = $$\frac{3}{4}y$$ 

= $$\frac{3}{4}\times52$$ 

= 39 cm​

The length of the shorter piece is 39 cm.