the total energy value of a 100g cereal is 20000 kj. the boy requires 5500 kj of energy per day. how many grams (g) of cereal does he need to eat in order to obtain this energy (assuming that he does not eat any other foods) show your working.
To find out how many grams of cereal the boy needs to eat, we can set up a proportion. Let's call the grams of cereal he needs to eat "x".
According to the information given, the total energy value of 100g of cereal is 20000 kJ.
We can set up the proportion as follows:
100g / 20000 kJ = x / 5500 kJ
To solve for x, we can cross-multiply:
100g * 5500 kJ = 20000 kJ * x
550000 kJ*g = 20000 kJ*x
Now, divide both sides by 20000 kJ to solve for x:
x = (550000 kJ*g) / 20000 kJ
x = 27.5g
Therefore, the boy needs to eat 27.5 grams of cereal in order to obtain 5500 kJ of energy.