What's the missing number?

Question

5 . 49 . ___ . 408 . 1227
What number fills the gap!?

Answer 1

sequence is 5,49, x,408,1227

here i will try a third order difference
(conjecture)

1st difference: 44,(x-49),(408-x),819

2nd difference:(x-93),(457-2x),
(x+411)

3rd difference: (550-3x),(-46+3x)

since i have a 3rd order difference,

550-3x= -46+3x

>>>>6x=596 >>>>x=99 1/3

it looks like the right answer and i will check with
a poly in n^3

i set up four equations using the 99 1/3
conjecture and swept out
A=42,B= -248 5/6,C=496.5
and D= -284 2/3 and therefore

for n =1,2,3,............

nth term= 42n^3-248 5/6n^2+496.5n-284 2/3

in the fibonacci sequence,the difference table
is always the same as opposed to a normal
polynomial induced sequence

i must admit this is the most difficult problem

set in the last 10 days-thanks

i hope that this helps

Answer 2

Richardallan is absolutely correct..

I would just like to add a footnote:-

The more terms you give in the question, the more accurate the answer will be.

For example, we all identify 0,1,1,2,3,5,8,12,.... as fibonacci series..

But if you give just 0,1,1,2,x,5 and you try to calculate x using this method, you will get 3.3

If you had given 0,1,1,2,x,5,8 and you try to calculate x using this method, you will get 2.75

This shows that we can form many series of the form 0,1,1,2,x,5 or 0,1,1,2,x,5,8 and not just the fibonacci series. We will arrive at the exact answer only when the number of terms given is large enough.

How large this number should be depends on the problem itself.

For example, the fibonacci series requires many numbers but a Arithmetic Progression like 1,3,x,7,9 requires just 2 numbers other than the missing term

Answer 3

64

Answer 4

261

Answer 5

251

Answer 6

224

Answer 7

The question needs to be more clear. I mean the 1st number is 5.49, 3rd as 0.408 etc.
Bcoz you have added dots (.) or decimals between numbers. It was better if use semi-colin (;) to separate two numbers instead.

Answer 8

hm >.> whats inbetween 49 and 408? something like 213?

xD i have no idea i quit maths 3 years ago... usless! where is this sum going to get you!

Answer 9

Sorry maths was my worst subject at school.Sorry but you are asking for a number in question and numbers in another which is it can you ammend the question to which it is please

Answer 10

do your own homework!