1. Calculate the percentages in the following cases:--
(a) Ore taken, 2 grams; copper found, 0.2155.
(b) " 1.5 gram; iron found, 0.8340.
(c) " 30 grams; lead found, 23.2.

2. Calculate the parts per thousand in the following:--
(a) Bullion taken, 1.1 gram; silver found, 1.017.
(b) " 1.14 gram; silver found, 1.026.
(c) " 0.6 gram; gold found, 0.5500.

3. Calculate parts per 100,000 in the following:--
(a) Ore taken, 20 grams; silver found, 0.0075.
(b) " 50 grams; gold found, 0.0026.
(c) Water taken, 500 c.c.; solids found, 0.1205.

4. Calculate cwts. to the ton in the following:--
(a) Ore taken, 5 grams; tin found, 2.816.
(b) " 5 grams; tin found, 3.128.
(c) An ore with 68.2 per cent. of tin.

5. Calculate lbs. to the ton in the following:--
(a) An ore with 3.28 per cent. oxide of tin.
(b) Ore taken, 20 grams; oxide of tin found, 1.67.

6. Calculate ozs. (troy) to the ton in the following:--
(a) Ore taken, 50 grams; gold found, 0.0035.
(b) " 20 grams; silver found, 0.0287.
(c) " 25 grains; silver found, 0.0164.

7. Calculate in grains per gallon:--