Help, YR 5 maths again - feeling dim

[purplepandas]

Hello,

Can anyone please help. I think the answers are 10, 45 and 99 but no idea re the last one. DD has no idea and no example. I actually have three degrees and am increasingly feeling v stupid with maths homework now ☹️. Any ideas how to help with the last one at all please?

I may be wrong with the 99 too.

Thank you
Pp

I think the last answer just wants to know if it would go up or down

The number of options not the ride

Thank you, I think you are right. Combinations would increase then, wouldn't they. I really do feel stupid and am v grateful!

It’s asking for the pattern/formula, so for the first one it’s 4+3+2+1, the second one is 9+8+7+6+5+4+3+2+1, so the last one is 99+98 etc etc. The quick way is (highest number + lowest) X number in sequence (so highest number -1) then divide by 2
So 4+1= 5, x 4 =20, / 2 =10
9+1=10, x9 = 90, /2 = 45
99+1=100, x 99 = 9900, / 2 = 4950

It says use the answers from the question before.

What was this question?

www.statisticshowto.datasciencecentral.com/calculators/permutation-calculator-and-combination-calculator/

You can cheat and type in the numbers here!
For 3 it stays the same for 5 (answer 10) but goes up For 10 and 100.

The last 2 questions are not asking for numerical answers, they are asking for explanations.

This was why I asked what the question before was, as they are asking about using that information to explain this answer.

One way you can do Q1 is
10 x 9
(10 different gods can sit on the first seat times 9 remaining gods which can sit on the second seat)

However this means every pair would be chosen twice so you then need to half your answer. (Which gives 45 like you have)

The advantage to this method is that is works just as well with 100 gods as it does 10.

Thanks all, I really appreciate it. I also wanted to know what the question before was but helpfully school did not include it. Really pisses me off when they do this with no example.

I am super grateful for the explanations. Now to explain to DD. for all!