This week the topic was calculus and differentiation. We talked to Florencia Tettamanti, who’s a mathematician working on fluid dynamics. We talked about how Flo uses calculus to study the motion of fluids like air and water, and what it’s like to be a research mathematician.

Solution:

If you plot the points x=1, x=2, x=3 and x=4 you can clearly see the curve of this graph and that it seems to have a maximum at x=3, for which the value of y is 4. To see what the graph looks like, you can input the equation into Wolfram Alpha.

Another way to see this is to rearrange the equation: x2-6x+13 = (x-3)2+4, and by examining this equation we can see that this is just an x graph, shifted across by 3 and up by 4, so its turning point and hence the minimum will be at x=3 and y=4.

If you know how to use calculus, you can find the turning point more easily - if you differentiate x2-6x+13 you get 2x - 6, which will equal zero when x=3, and putting this value back into the original equation gives y=4.

This week the topic was mechanics and friction. We interviewed Dan Hett, who works for CBBC writing computer games for their website. We talked about his work and how he uses a lot of mathematics in modelling how characters move, and making sure that’s done in a realistic way.

Solution:

This week the topic was Fourier analysis. We interviewed Heather Williams, who’s a medical physicist and works with Positron Emission Tomography (PET) scanners, as well as other medical scanning devices. We talked about her work and how maths is important in converting data from the scanner into images that can be used to diagnose patients.

Solution:

This week the topic was mathematical modelling and linear programming. We interviewed Rick Crawford from AMEC, who’s a mathematician studying decommissioning of nuclear reactors, and using mathematical models to determine whether it’s safe to continue using a particular reactor given that it may have degraded over time, but without actually building a physical model of it.

Solution:

This week the topic was statistical distributions and actuarial science. We interviewed Richard Harland, who works in risk management for an insurance firm. We talked to him about his work as an actuary, and how he uses statistical distributions like the normal distribution to predict the probability of risky events.

Solution:

This week the topic was mathematics and money, and how maths is used in finance. We interviewed Sarah O’Rourke, who’s an accountant working on the problem of moving cash around to where it’s needed in cash machines. We discussed the ways she uses mathematical modelling to predict where demand for cash will be high, and also the other types of work that accountants do, and the different ways to become an accountant.

1. Using only £20 and £50 notes, what’s the largest multiple of £10 you can’t make?

Solution:

This week the topic was maths and art. We interviewed Edmund Harris, who spoke about his work using different media to engage people with mathematics, including his work creating art with a mathematical basis. We discussed his work with tilings and how he uses maths in his work.

This week the topic was vectors and matrices. We interviewed Dave Langers, who studies the human brain, and how it processes hearing signals. We talked about how Dave uses matrices and vectors to store information from brain scans, which allow him to manipulate the information more easily.

Solution:

2 × (1,3,1,3) - (2,2,6,6) - (4,8,8,12) = (0,0,0,0)

This week the topic was data analysis. We interviewed Judith Elgie from INRIX about her work as a data analyst, and how she uses computers to analyse and predict the movement of vehicles on the roads, to generate information about where traffic jams are and which roads are clear.

Solution:

This week the topic was boolean algebra. We interviewed Robie Basak, who's a computer programmer at Canonical, about his work on the Ubuntu operating system, and how he and his colleagues use mathematics and mathematical thinking in order to write computer software.

Solution:

Anna states they are both knaves; this can’t be true, as if it were she would be a knave and therefore would be lying. So, the statement must be false, and Anna is therefore a knave. Also, since she always lies, they can’t both be knaves, so Bill must be a knight.

In the second example, the two give different answers, one of which must be true, so one of them must be lying, and therefore Diane is telling the truth. This means Chris is a knave and Diane is a knight.