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How do I find the volume of a sphere?

The equation for the volume of a sphere is:v = 4/3 x pi x r^3 from this we can see the information we need to find out is the radius of sphere. in this example the radius is 2cm. therefore, the volume is: v ...
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Answered by Luke C. • Maths tutor
4959 Views

There are 10 boys and 20 girls in a class. The mean mark in a test for all the class is 60. The mean mark for the girls is 54. Work out the mean mark for the boys.

First let us consider how we calculate the mean test mark in the first place, we add up the individual test marks of the entire class to give the total test mark then we divide by the number of students. Thi...
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Answered by Adam D. • Maths tutor
68148 Views

A GCSE is graded out of 140 marks. 1/5 of these marks were given for coursework. The rest were divided between two reading and listening tests, with the marks split in the ratio 3:4 respectively. How many marks were given for the reading test?

140/5 = 28140 - 28 = 1123 + 4 = 7112/7 = 1616 x 3 = 48Answer: 48 (Would go through methods with student: order of thinking, dealing with ratio, long division)
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Answered by Will B. • Maths tutor
4436 Views

The equation 5x^2 + px + q = 0, where p and q are constants, has roots t and t+4. Show that p^2 = 20q + 400.

We know that if we have a polinomial of the form ax^2 + bx + c = 0, then:sum of the roots = -b/a and product of the roots = c/a Therefore: t + (t + 4) = -p/5 and t(t + 4) = q/5 Therefore: 2t + 4 = -p/5 so t ...
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Answered by Alexandra B. • Maths tutor
5148 Views

Solve the simultaneous equations: 3x+5y=19, 4x-2y=-18

For all simultaneous equations it is useful to number each one to keep your working clear and concise. In order to solve this we need to eliminate one of the variables (x or y) by manipulating the equations....
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Answered by Ben W. • Maths tutor
10050 Views