# Tutor profile: Ved S.

## Questions

### Subject: SAT II Mathematics Level 2

If a certain score distribution has the following properties: Mean : 70 Median : 73 Standard deviation : 10 What would change after a curve of 5 points for each student?

You don't need to know any formulae to answer this question, so its okay if standard deviation confuses you. Just think about each term conceptually. If everyone's score increases, will the average value also change? Yes, so the mean will go up 5 points. If I arrange the scores in an increasing order, note the score in the middle, and then increase each score by 5 points, will the middle score also change? Yes, so the median will increase by 5. Standard deviation is just how far each score is from the mean. If the mean increased by 5, because each score increased by 5, then the distance to the mean would remain constant, so the standard deviation won't change.

### Subject: Python Programming

Why would you want to use NumPy arrays instead of lists in Python?

Speed is probably the most important aspect. Arrays are much faster in the sense that reading and writing values is more efficient. This is also because arrays take up less memory than standard lists. Another huge advantage of arrays is the availability of linear algebraic operations. In the fields of finance and statistics, it is essential to be able to execute large-scale mathematical functions on a set of data, and that is substantially easier to do with arrays.

### Subject: Physics

Why does the sky look blue normally but red/yellow during a sunset?

Our atmosphere is made up of tiny gas molecules, mainly comprised of Oxygen and Nitrogen. Sunlight is made up of all kinds of different wavelengths, essentially all kinds of colors. During the day, the sun is right above our heads so the light has to travel a smaller distance to reach our eyes. During this small time, blue light is scattered by the gas molecules in all directions, leading to a blue sky. During sunset, the sun is slightly distant from us, due to the Earth's rotation. The extra distance leads to the blue light being completely scattered, or removed, before reaching our eyes. So by the time the light reaches our eyes, only red and yellow light remain.

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