# Tutor profile: Harry R.

## Questions

### Subject: Geometry

The circumference of a circle is 30. What is its area?

The circumference of a circle is given by the formula C = 2*pi*r, where r is the radius of the circle. Substitute the given circumference into this formula and solve for r. 30pi = 2*pi*r r = 15 Therefore, the radius of the circle is 15. Use this to find the area of the circle. The area of a circle is given by the formula A= pi*r^2. Substitute the length of the radius into this formula and calculate the area. A =pi*(15)2 = 225pi Therefore the answer is 225pi

### Subject: Basic Math

The exam scores of all 500 students were recorded and it was determined that these scores were normally distributed.If Jane's score is 0.8 standard deviation above the mean, then how many, to the nearest until,students stored above Jane?

The exam scores of all 500 students were recorded and it was determined that these scores were normally distributed.If Janes score is 0.8standard deviation above the mean, then how many, to the nearest until,students stored above Jane? Z score = ( score - Mean) / Standard deviation => Z score = ( Mean + 0.8 Standard deviation - Mean)/Standard deviation => Z score = 0.8 Standard deviation/Standard deviation => z score = 0.8 z score 0.8 = 78.81 % ( see attached z score table) Number of students who scored more than Jane = 100 - 78.81% = 21.19 % 21.19 % of 500 = (21.19/100) * 500 = 105.95 = 106

### Subject: Mechanical Engineering

What is a machine?

A machine is a device that simply transforms the direction or magnitude of a force, but a large number of more complex machines exist. Examples include vehicles, electronic systems,molecular machines, computers, television, and radio.

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