Relative to an origin O, points A, B and C have position vectors (5/4), (-10/12) and (-6/-18) respectively. All distances are measured in kilometres. A man drives at a constant speed directly from A to B in 20 minutes.
- (i)Calculate the speed in kmh⁻¹ at which the man drives from A to B.[3]
- (ii)He now drives directly from B to C at the same speed. Find how long it takes him to drive from B to C.[3]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2015). The mark or mark type is shown in brackets.
- [B1] (i) AB=(-15/8) Allow BA May be implied by later work.
- [M1] (i) |AB| = √15² +8² (=17) Use of Pythagoras on their AB
- [A1] (i) Speed = 17×3 = 51km/hr Must be exact
- [B1] (ii) BC =(16/-30) Allow CB
- [M1] (ii) |BC| = √16² +30² (=34) Use of Pythagoras on their BC
- [A1] (ii) Time taken = 34/51 × 60 = 40 mins (or 2/3 hrs) Allow answers which round to 40 to 2sf. Accept 0.66 or 0.67 hrs. Mark final answer.
Write your answer and get it marked
On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.
Sign up free →