Chris Graham

Chris Graham commented on Partial sum of an arithmetic sequence - birthday money 8 years, 4 months ago

Sorry, you are quite right, I meant to say interest! If you are wording the question in a way that it is "What contribution...?" then you don't really need this anyway, so I have removed those references.

Chris Graham commented on Partial sum of an arithmetic sequence - birthday money 8 years, 4 months ago

As discussed, the sum of candles on a birthday cake over several years makes little sense either. Why would you want to know? 

Parents adding money to a bank account is much better, and then you could ask (excluding inflation) how much money the parents have added over $n$ years. 

This can also be split into two parts, firstly calculate $a_n$ for the given $n$, and then the sum of the series, with a step for each part.

Chris Graham commented on Arithmetic sequences in an ice cream shop 8 years, 4 months ago

Elliott, since you've been working on this one already, can we add a step with the equation for an arithmetic sequence and gaps for the first value and difference. In addition, let's put everything before "How many customers..." into the statement.

Chris Graham on Arithmetic sequences in an ice cream shop 8 years, 4 months ago

Gave some feedback: Has some problems

Chris Graham commented on Transformation - Translation 8 years, 4 months ago

Looks good. I've removed the additional gap, which was causing an error on submission. 

Chris Graham on Transformation - Translation 8 years, 4 months ago

Gave some feedback: Ready to use

Chris Graham commented on Partial sum of an arithmetic sequence - birthday money 8 years, 4 months ago

The step doesn't give enough useful information, and neither does it give the opportunity for the student to break down the question: so the first step would be to find $a_n$, but the step doesn't tell me how to do that. There's an easy opportunity to have gaps here for the common difference, the final term, and so on.

I also have major issues with the context. I'm led to believe Bruce receives 93 slices of his birthday cake on his 50th birthday. How big are these slices? I can only assume that they are getting smaller at a rate inversely proportional to the increase in slices. How about changing to the number of candles? 93 candles on a cake is still a stretch, but slightly more plausible. 

Chris Graham on Partial sum of an arithmetic sequence - birthday money 8 years, 4 months ago

Gave some feedback: Has some problems

Chris Graham commented on Ways of rolling two dice 8 years, 4 months ago

I think that students will find this very confusing indeed. You give an answer at the top, 11 possible outcomes, and refer to an "outcome" as the total value of the two dice. But in the question you are expecting the students to interpret the word "outcome" as the possible values $(a,b)$ that the dice could take.  

I'm also not certain of the benefit of this sort of question to an incoming student.

Chris Graham on Ways of rolling two dice 8 years, 4 months ago

Gave some feedback: Has some problems