Jake makes concrete by mixing cemente, sand and gravel in the ratio 4:2:1 work out the mass of the sand in 38.5kg of concrete mix

11kg

Step-by-step explanation:

In order to answer this question you need to find out how much cement, sand and gravel is needed to make 38.5g of concrete mix. To do this you must find out how many parts the concrete mix ratio is made up (4 + 2 + 1 = 7) Then divide the total concrete mix (38.5kg) by the number of parts; 38.5/7 = 5.5. This tells you that each of the 7 parts of the ratio = 5.5kg. As the ratio tells you sand is 2 parts you multiply this by 5.5 (2 x 5.5kg = 11kg).

You divide 38.5 by 7 then times your answer by 2

The answer is 1.4285kg