# 10cm^3 of normal specimen of human blood contains 1.2g of hemoglobin. How many grams does 35cm^3 of the same blood contain?

Sep 17, 2016

$4.2 g$

#### Explanation:

You can do this using 2 methods:

Method 1: The unitary method where you work out for 1 $c {m}^{3}$

In $10 c {m}^{3}$ of blood .... $1.2 g$

In $1 c {m}^{3}$ of blood ....$1.2 \div 10 = 0.12 g$

In $35 c {m}^{3}$ of blood ....$35 \times 0.12 g = 4.2 g$

Method 2: The direct proportion or comparison method

$\frac{10 c {m}^{3}}{35 c {m}^{3}} = \frac{1.2 g}{x g} \text{ } \rightarrow$ cross-multiply

$10 \times x = 35 \times 1.2$

$x = \frac{35 \times 1.2}{10}$

$x = 4.2 g$