Hello everyone,

Could someone please help me with this double false position problem?

A buisness man doubled his money and he spent $12. He then left and doubled his money in another city and spent $12. He returned and doubled his money, and spent $12. At the end of the 3 trips and after the expenses he has $9 left. How much did he have at the begining?

I know the answer is 11.625

Do you see where I went wrong?

the algebraic way:

(2x-12)+(2x-12)+(2x-12)=9

6x=45

x=7.5

Double false position:

Guess $100

($100)2-12=188

($100)2-12=188

($100)2-12=188

________________

564

564-9=555

Guess #2 $50

(50)2-12=88

(50)2-12=88

(50)2-12=88

__________

264

264-9=255

100 555

50 255

cross multiply: (100)(255)=25500

(50)(555)=27750

Take the difference:

27750-25500=2250

2250/difference in error=

2250/555-255 =

7.5

Thank you very much