Currency Exhange

Question

If £1=€1.20 and €0.90=$1.40 how much is $150 in £ and why?

Answer 1

If £1=€1.20 and €0.90=$1.40 how much is $150 in £  ⇔ $1.00 = €0.90/1.40 =€0.6428, truncated to 4 dec. places.

 

$150 = 150 • €0.6428 = € 96.43 **

 

If £1=€1.20 then € 1 =  £1/1.2 = £ 0.8333

 

Mlultiplying the number of euros (**) by the above factor, we get  £ 80.35

Answer 2

When converting units without changing the value, we use the Multiplicative Identity (that is, 1).  Any value multiplied by 1 remains the same.

 

For this problem:

    1  =  ( £1 ) / ( €1.20 )  =  ( €1.20 )/( £1 )                

    1  =  ( €0.90 ) / ( $1.40 )  =  ( $1.40 ) / ( €0.90 )

 

How much is $150 in £ ?

      $150

      ( $150 ) * 1

      ( $150 ) * (( €0.90 ) / ( $1.40 )) * (( £1 ) / ( €1.20 ))      [choose the ratioes that cancel units]

      £(150)*(0.90/1.40)*(1/1.20)        [$ and € cancel)

      £80.35714    (but it would be rounded)