maths -number sequence

[kaya]

Pls help, my DD can't work these out. Neither can I!!

1. What is the answer to this nimber sequence
1 2 4 8 10 20 ____ ____ .

Please explain

2. Paul is given a box of 45 chocolates. His brother eats 20%and his mum eats 2/5. How many chocolates are left for Paul?

[Twinkle]

Question 2: Answer = 18

20% = 1/5. So 3/5 are eaten ie 27 ( 45 divided by 5 = 9. Then x 3). Therefore 45 - 27 = 18.

[Twinkle]

Question 1:

The next two nos are 22 and 44.

THere are two difference alternating sequences here:

1,4 10 22

and

2,8,20 and 44

The difference between the nos in the first sequence doubles, so the differences are 3,6,12

The difference between the nos in the second sequence doubles too, so the differences are 6, 12, 24

[hbsmum]

Question 1: The pattern is x2, +2 so the next two numbers are 22, 44

[chicko-mum]

DD thinks the first one is a leapfrog sequence, ie 2 sequences in one

1..... 4..... 10..... ?
+3 +6 therefore next in sequence is +12 so 1st ? is 22

2..... 8 ..... 20 ..... ?
+6 +12 therefore next in sequence is +24 so 2nd ? is 44


The second problem is...
Paul is given a box of 45 chocolates. His brother eats 20% ie 1/5
and his mum eats 2/5. How many chocolates are left for Paul? so 1/5 + 2/5 = 3/5 have been eaten, this leaves 2/5 of 45 = 18 chocs left for Paul.

[Twinkle]

Gosh how interesting that we have approached question 1 completely differently and got the same answers!

[kaya]

Hi guys,

Thanks for answering so promptly. DD and I understand it now.

[abr]

I totally understand the approach for Q1 (the number sequence) with answers 22 and 44.It makes complete sense.

But when given this question, one of the answers that came up in the discussion at home was :

1, 2,4,8, 10, 20, 40, 80, 100, 200, 400, 800, 1000, 2000, 4000, 8000 and so on.

In this case, the next two numbers would be 40, 80.
This is a sequence of repetitions. Shouldn't this kind of approach be ever applied for a 11+ Maths ?

[Twinkle]

I think that there is not sufficient evidence in the string of nos given in the question for that type of approach.

[sherry_d]

Thats what I thought at first too Abr but then there is 8 to 10 which throws out that sequence.