Javier and Stella are planning their exercise routines. Javier and Stella have a body mass of 70 kg and 60 kg respectively. The speed for walking and jogging of the two individuals are represented in the chart.

1. Find the total calories burned by each person for the four brisk walks and compare them.

The four walks together take $150$ minutes.

Since $150 \div 30 = 5$, multiply the 30-minute calorie values by $5$.

Using the Walking $6.5$ km/h row:

Javier, $70$ kg: $150 \times 5 = 750$ calories

Stella, $60$ kg: $130 \times 5 = 650$ calories

Difference:
$750 - 650 = 100$

1. Check whether Javier meets the target for additional health benefits.

For Javier's walks:
$\text{time for one walk}=\frac{4}{6}\text{ h}=\frac{2}{3}\text{ h}=40\text{ min}$
$\text{total walking time}=3\times 40=120\text{ min}$

For Javier's jogs:
$\text{time for one jog}=\frac{6}{8}\text{ h}=0.75\text{ h}=45\text{ min}$
$\text{total jogging time}=2\times 45=90\text{ min}$

Since $1$ min vigorous $=2$ min moderate,
$90\text{ min jogging}=180\text{ min moderate-equivalent}$

Total moderate-equivalent time:
$120+180=300\text{ min}$

So Javier meets the target for additional health benefits.

2. Check whether Stella meets the target for optimal health benefits.

For Stella's jogs:
$\text{time for one jog}=\frac{8}{10}\text{ h}=0.8\text{ h}=48\text{ min}$
$\text{total jogging time}=2\times 48=96\text{ min}$

Stella needs at least $75$ min of vigorous-intensity aerobic activity.

Since $96>75$, Stella meets the target for optimal health benefits.

3. Calculate Javier's total calories burned per week.

Javier has mass $70$ kg.

Walking calories: use Walking $6.5$ km/h, $70$ kg: $150$ calories per $30$ min.
$\text{walking calories}=\frac{120}{30}\times 150=600$

Jogging calories: use Jogging $8$ km/h, $70$ kg: $280$ calories per $30$ min.
$\text{jogging calories}=\frac{90}{30}\times 280=840$

Yoga calories:
$45\text{ min}\times 2=90\text{ min}=1.5\text{ h}$
$\text{yoga calories}=1.5\times 3\times 70=315$

Total calories burned by Javier:
$600+840+315=1755$

4. Calculate Stella's total calories burned per week.

Stella has mass $60$ kg.

Jogging calories: use Jogging $9.5$ km/h, $60$ kg: $300$ calories per $30$ min.
$\text{jogging calories}=\frac{96}{30}\times 300=960$

Weight training calories:
$30\text{ min}\times 2=60\text{ min}=1\text{ h}$
$\text{weight training calories}=1\times 4\times 60=240$

Total calories burned by Stella:
$960+240=1200$

5. Compare Javier's calories with Stella's and decide whether Javier's statement is correct.

Difference in calories:
$1755-1200=555$

Percentage more than Stella:
$\frac{555}{1200}\times 100\%=46.25\%$

This is about $50\%$ more.

Both also do muscle-strengthening activities on $2$ days per week, so they meet that part of the advice.