Liquid A and liquid B are mixed together in the ratio 2:13 by volume to make liquid C - Edexcel - GCSE Maths - Question 14 - 2019 - Paper 3

Since liquid A and B are mixed in a ratio of 2:13, the total ratio parts = 2 + 13 = 15.

The volume of liquid A:

$V_A = V_C \times \frac{2}{15} = 706.86 \times \frac{2}{15} \approx 94.25 \, cm^3$

The volume of liquid B:

$V_B = V_C \times \frac{13}{15} = 706.86 \times \frac{13}{15} \approx 612.61 \, cm^3$

Using the density of liquid A, we find its mass by using the formula:

$\text{mass} = \text{density} \times \text{volume}$

For liquid A:

$m_A = 1.21 \, g/cm^3 \times 94.25 \, cm^3 \approx 114.06 \, g$

Using the density of liquid B, we find its mass:

For liquid B:

$m_B = 1.02 \, g/cm^3 \times 612.61 \, cm^3 \approx 624.92 \, g$

The total mass of liquid C is:

$m_C = m_A + m_B \approx 114.06 \, g + 624.92 \, g \approx 738.98 \, g$

This is rounded to 739 g to 3 significant figures.