These problem can be solved using conversion fractions. A conversion fraction is a unitary fraction that we use to convert units; the idea is multiply the unit we want to convert by a fraction with the same unit as denominator and the target unit as numerator.
First, we are going to find how many grams are [tex] \frac{3}{4} [/tex] lb. Since we know that [tex] 1lb = 450g [/tex], we just need to multiply [tex] \frac{3}{4}lb [/tex] by the conversion fraction [tex] \frac{450g}{1lb} [/tex]:
Grams per person = [tex] (\frac{3}{4}lb)(\frac{450g}{1lb} )=(0.75lb)(\frac{450g}{1lb} )=337.5g [/tex]
Next, we are going to find the total amount of grams Adam will need. Since there are 14 persons, we just need to multiply the grams per person by 14:
Total grams = [tex] 14(337.5g)=4725g [/tex]
Since the cost of the turkey is expressed in kilograms, we need to convert the total grams to kilograms. We know that 1 kg = 1000 g, so we need to multiply the total grams by the conversion factor [tex] \frac{1kg}{1000g} [/tex]:
Total kg = [tex] (4725g)(\frac{1kg}{1000g} )=4.725kg [/tex]
Now we know know that Adam will need to buy 4.725 kg of medium size turkey, so the only thing left is multiply the price of the medium size turkey by the total kg:
Total cost = [tex] (4.725kg)(\frac{5.99}{kg} )=28.30 [/tex]
We can conclude that a turkey for 14 people will cost £28.30.
