Secondary School (English Medium) (5 to 8) Class 8 - CBSE Question Bank Solutions for Mathematics

In 10 days, the earth picks up 2.6 × 10⁸ pounds of dust from the atmosphere. How much dust will it pick up in 45 days?

In 15 days, the earth picks up 1.2 × 10⁸ kg of dust from the atmosphere. In how many days it will pick up 4.8 × 10⁸ kg of dust?

If \[x^2 + \frac{1}{x^2} = 18,\]  find the values of \[x + \frac{1}{x} \text { and } x - \frac{1}{x} .\]

If x + y = 4 and xy = 2, find the value of x² + y²

If x − y = 7 and xy = 9, find the value of x² + y²

If 3x + 5y = 11 and xy = 2, find the value of 9x² + 25y²

Find the value of the following expression: 16x² + 24x + 9, when \[x = \frac{7}{4}\]

Find the value of the following expression:  64x² + 81y² + 144xy, when x = 11 and \[y = \frac{4}{3}\]

Find the value of the following expression:  81x² + 16y² − 72xy, when \[x = \frac{2}{3}\] and  \[y = \frac{3}{4}\]

If x² + y² = 29 and xy = 2, find the value of x + y.

If x² + y² = 29 and xy = 2, find the value of x - y.

Rohan can paint \[\frac{1}{3}\]  of a painting in 6 days. How many days will he take to complete the painting?

If x² + y² = 29 and xy = 2, find the value of x⁴ + y⁴ .

Anil can do a piece of work in 5 days and Ankur in 4 days. How long will they take to do the same work, if they work together?

Mohan takes 9 hours to mow a large lawn. He and Sohan together can mow it in 4 hours. How long will Sohan take to mow the lawn if he works alone?

Sita can finish typing a 100 page document in 9 hours. Mita in 6 hours and Rita in 12 hours. How long will they take to type a 100 page document if they work together?

A, B and C working together can do a piece of work in 8 hours. A alone can do it in 20 hours and B alone can do it in 24 hours. In how many hours will C alone do the same work?

A and B can do a piece of work in 18 days; B and C in 24 days and A and C in 36 days. In what time can they do it, all working together?

A and B can do a piece of work in 12 days; B and C in 15 days; C and A in 20 days. How much time will A alone take to finish the work?