1.

at present a mother is twice as old as his daughter. twenty years back their ages were in the ratio of 10 : 3 .The present age of the mother is​

Answer»

ong>Answer:

the present age of the mother is 70

i hope this helps!!

Step-by-step explanation:

let us take the present age of the mother as x and the present age of her daughter as y

  • "at present a mother is twice as old as her daughter" so,
  • we get the first equation as x = 2y from this.
  • "twenty years back their ages" Now, 20 years ago, their ages will be 20 years less., so, the past age of the mother is 20-x and the past age of the daughter is 20-y
  • "twenty years back their ages were in the ratio of 10 : 3" since ratio is a fraction, we can SAY that  \frac{20-x}{20-y} = \frac{10}{3}

substituting the x with the first equation so we get:

\frac{20-(2y)}{20-y} = \frac{10}{3}

now we cross multiply, which gives us,

=> 3(20-2y) = 10(20-y)

=> 60 - 6y = 200 - 10y

=> - 6y + 10y = 200 - 60

=> 4y = 140

=> y = \frac{140}{4}

=>y = 30

to find the mothers present age, we USE the first equation;

x = 2y

x = 2×35

x = 70


Discussion

No Comment Found

Related InterviewSolutions