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**cat1kf2****Member**- Registered: 2012-11-15
- Posts: 3

After 3 days, there are 1,600 bacteria. How many bacteria were there at the beginning of the first day? Use the work backward strategy.

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,340

hi cat1kf2

Welcome to the forum.

Work backwards:

After 3 days ....................1600

12 hours earlier................ 1600 ÷ 2

after two days .................. ÷ 2 again

12 hours earlier ................ ÷ 2 again

After one day ................... ÷ 2 again

12 hours ealier ................. ÷ 2 again

start ................................ ÷ 2 again

Bob

Children are not defined by school ...........The Fonz

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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**SMBoy****Banned**- Registered: 2012-11-17
- Posts: 13

Is The Answer above correct? as there is no reply?

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,340

hi SMboy,

Welcome to the forum.

What answer are you talking about ?

I gave a method, but deliberately did not say what I thought the answer is.

Bob

Children are not defined by school ...........The Fonz

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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**Ms_Zee****Guest**

Hi SMboy,

The explanation you received from bob bundy is correct, you just need to work out the result.

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**Mathegocart****Member**- Registered: 2012-04-29
- Posts: 1,917

according to bob bundy(thank you)

the Awser is 25

The integral of hope is reality.

May bobbym have a wonderful time in the pearly gates of heaven.

He will be sorely missed.

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**SMBoy****Banned**- Registered: 2012-11-17
- Posts: 13

Thank's all I understand now how it works.

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**cat1kf2****Member**- Registered: 2012-11-15
- Posts: 3

bob bundy wrote:

hi cat1kf2

Welcome to the forum.

Work backwards:

After 3 days ....................1600

12 hours earlier................ 1600 ÷ 2

after two days .................. ÷ 2 again

12 hours earlier ................ ÷ 2 again

After one day ................... ÷ 2 again

12 hours ealier ................. ÷ 2 again

start ................................ ÷ 2 again

Bob

Thanks for your help Bob

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**cat1kf2****Member**- Registered: 2012-11-15
- Posts: 3

mathgogocart wrote:

according to bob bundy(thank you)

the Awser is 25

thanks for your help

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