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8 grade maths

At present, Asha’s age (in years) is 2 more than the square of her daughter Nisha’s age. When Nisha grows to her mother’s present age, Asha’s age would be one year less than 10 times the present age of Nisha. Find the sum of their present ages.

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11 Months agoGrade
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1 Answer

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ApprovedApproved Tutor Answer11 Months ago

To solve the problem regarding Asha and Nisha's ages, we can set up a couple of equations based on the information provided. Let's break it down step by step.

Defining Variables

First, we need to define the ages of Asha and Nisha. Let's denote:

  • A = Asha's current age
  • N = Nisha's current age

Setting Up the Equations

According to the problem, we have two key pieces of information:

  • Asha’s age is 2 more than the square of Nisha’s age.
  • When Nisha reaches Asha’s current age, Asha will be one year less than 10 times Nisha’s current age.

From the first piece of information, we can write the equation:

A = N² + 2

For the second piece of information, we need to determine how many years it will take for Nisha to reach Asha's current age. This will be:

A - N years.

At that time, Asha’s age will be:

A + (A - N) = 2A - N

According to the problem, this age will be one year less than 10 times Nisha's current age:

2A - N = 10N - 1

Solving the Equations

Now we have a system of two equations:

  • 1. A = N² + 2
  • 2. 2A - N = 10N - 1

Let's substitute the first equation into the second equation:

2(N² + 2) - N = 10N - 1

Expanding this gives:

2N² + 4 - N = 10N - 1

Rearranging the equation leads to:

2N² - 11N + 5 = 0

Applying the Quadratic Formula

This is a quadratic equation in standard form, which we can solve using the quadratic formula:

N = (-b ± √(b² - 4ac)) / 2a

Here, a = 2, b = -11, and c = 5.

Calculating the discriminant:

b² - 4ac = (-11)² - 4(2)(5) = 121 - 40 = 81

Now substituting back into the formula:

N = (11 ± √81) / 4 = (11 ± 9) / 4

This gives us two potential solutions for N:

  • N = (20) / 4 = 5
  • N = (2) / 4 = 0.5 (not a valid age)

Finding Asha's Age

Since Nisha's age must be a whole number, we take N = 5. Now we can find Asha's age:

A = N² + 2 = 5² + 2 = 25 + 2 = 27

Calculating the Sum of Their Ages

Now that we have both ages:

  • Asha's age (A) = 27 years
  • Nisha's age (N) = 5 years

The sum of their present ages is:

27 + 5 = 32

Final Answer

Thus, the sum of Asha and Nisha's present ages is 32 years.