Ihave no idea: david drove a distance(d) of 187km, to 3 sig. fig. he used 28 litres of petrol(p), to 2 sig. fig. the petrol consumption(c)in km per litre is given by the formula: c= d/p by considering bounds, work out the value of c, to a suitable degree of accuracy. you must show your working and give a reason for your answer. you!

So we have the formula: 
where 
is the distance in kilometers 
is the petrol in liters 
is the petrol consumption in kilometers per liter 

We now for our problem that  David drove a distance of 187 km, so . We also know that  he used 28 liters of petrol, so . Lets replace those values in our formula to find the petrol consumption:




Now, remember that are some rules to determine the number of significant figures in a number:
1. Non-zero digits are always significant figures.
2. A zero between tow significant figures is always a significant figure.

Applying those tow rules we realize that has 6 significant figures, whereas  has three significant figures and  only two. In mathematical operations with significant figures, the answer should be given with the same significant figures as the number with least significant figures involved in the operations. In our case, that number is , and  has two significant figures, so our answer should have 2 significant figures. To give our answer with 2 significant figures, we are going to round it:



We can conclude that the patrol consumption of David's vehicle is 6.7 kilometers per liter.