Higher Plus

A bag holds 11 counters, r of them red. Two are taken without replacement and P(both red) = 3/55. Work out r.

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

A block has mass 430 g (to the nearest 10 g) and volume 20 cm³ (to the nearest cm³). Work out the upper bound of its density, to 2 decimal places.A block has mass 430 g (to the nearest 10 g) and volume 20 cm^3 (to the nearest cm^3). Work out the upper bound of its density, to 2 decimal places.

Prove that the sum of 5 consecutive integers is always a multiple of 5. State the simplified sum you would use.

y is inversely proportional to x². When x = 4, y = 50. Work out y when x = 5.y is inversely proportional to x^2. When x = 4, y = 50. Work out y when x = 5.