(i) The denominator of a fraction is 1 less than twice its numerator. If 1 is added to numerator and denominator respectively, the ratio of numerator and denominator is 3: 5. Find the fraction.
Denominator of a fraction is 1 less than twice its numerator. If 1 is added to numerator and denominator respectively, the ratio of numerator and denominator is 3: 5.
Required Answer:–
Let us consider that the numerator of the fraction is x and the denominator be y. Then the fraction will be [tex]\frac{x}{y}[/tex].
According to question,
The denominator of a fraction is 1 less than twice its numerator. That means,
[tex]y = 2x – 1..(1)[/tex]
We can keep this equation in this way. Later, we can try solving by substitution.
Also,
If 1 is added to numerator and denominator respectively, the ratio of numerator and denominator is 3 : 5. That means,
[tex] \dfrac{x + 1}{y + 1} = \dfrac{3}{5} [/tex]
Cross multiply to get an equation,
[tex]5(x + 1) = 3(y + 1)[/tex]
Opening the parentheses,
[tex]5x + 5 = 3y + 3[/tex]
[tex]5x – 3y + 2 = 0[/tex]
Now from equation (1), substitute y = 2x – 1,
[tex]5x – 3(2x – 1) + 2 = 0[/tex]
Simplifying the above equation,
[tex]5x – 6x + 3 + 2 = 0[/tex]
[tex] – x + 5 = 0[/tex]
[tex] – x = – 5[/tex]
And,
[tex]x = 5[/tex]
Then,
[tex]y = 2(5) – 1 = 9[/tex]
And the required fraction will be [tex]\boxed{\frac{5}{9}}[/tex].
How to check?
Given :-
Denominator of a fraction is 1 less than twice its numerator. If 1 is added to numerator and denominator respectively, the ratio of numerator and denominator is 3: 5.
To Find :-
The fraction
Solution :-
Let the numerator be x
And denominator will be 2x – 1
[tex]\sf \dfrac{x + 1}{2x – 1 + 1} = \dfrac{3}{5}[/tex]
[tex]\sf\dfrac{x+1}{2x} = \dfrac{3}5[/tex]
By cross multiplication
3(2x) = 5(x + 1)
6x = 5x + 5
6x – 5x = 5
x = 5
Finding the fraction
[tex]\sf Fraction =\dfrac{5}{2(5)-1}[/tex]
[tex]\sf Fraction = \dfrac{5}{10-1}[/tex]
[tex]\sf Fraction = \dfrac{5}{9}[/tex]