# When processing a part from a casting weighing 40 kg, 3.2 kg was spent as waste.

**When processing a part from a casting weighing 40 kg, 3.2 kg was spent as waste. What is the percentage of the mass of the part from the mass of the casting? When sorting grain from 1750 kg, 105 kg were used as waste. What percentage of grain is left?**

1. Let’s find what the mass of the manufactured part is equal to minus the mass of waste:

1) 40 – 3.2 = 36.8 (kg).

Let’s find out what percentage the given mass is from the mass of the casting. To do this, you need to find the ratio of these masses and multiply by 100%:

2) 36.8 / 40 * 100 = 92 (%).

Answer: the mass of the part is 92% of the mass of the casting.

2. Let’s find the amount of grain left after waste removal:

1) 1750 – 105 = 1645 (kg).

Let’s find the percentage of the remainder of the original amount:

2) 1645/1750 * 100 = 94 (%).

Answer: The remaining percentage of grain is 94% of the original weight.