Luiz and Bianca are brother and sister and go to the same school. Luiz walks to school using a footpath, a distance of 900 m, and he walks at 1.5 m/s. Bianca cycles to school along the roads, a distance of 1.5 km, and she cycles at 5 m/s. They both plan on arriving at school by 8.55 a. m. Who leaves home first and by how much?

Luis leaves home first and he leaves 5 minutes before Bianca

Step-by-step explanation:

dL (distance travelled by Luis) = 900 m

sL(Luis'd speed) = 1.5 m/s

tL = time taken by Luis = dL/sL =  900/1.5 = 600 seconds =  10 mins

So Luis would need to leave home at 8:45 am

dB = 1.5 km = 1500 m

sB = 5 m/s

tB = dB/sB = 1500/5 = 300 seconds = 5 minutes

So Biance would leave home at 8:50 am