Higher Plus

A bag holds 8 red and n blue counters. The probability of taking a red is 4/5. Work out n.

A histogram has four 10-wide classes from 0, with frequency densities 1, 2, 0.5, 3. Which class contains the median?

A block has mass 810 g (to the nearest 10 g) and volume 15 cm³ (to the nearest cm³). Work out the upper bound of its density, to 2 decimal places.A block has mass 810 g (to the nearest 10 g) and volume 15 cm^3 (to the nearest cm^3). Work out the upper bound of its density, to 2 decimal places.

Solve 4x² - 1 = 0.Solve 4x^2 - 1 = 0.

y is inversely proportional to x². When x = 2, y = 100. Work out y when x = 5.y is inversely proportional to x^2. When x = 2, y = 100. Work out y when x = 5.