Maths!!!

1)Tommy spent 60s to complete 400m on a runnimg machine, what was his speed? (Correct to 3 significant figures.)

∵speed = distance/time
∴ his speed
=400/60
= 6.67 ms-1 (Correct to 3 significant figures.)



2)The weight of Gary is measured to be 65kg with a percentage error of 4%. Find the range of his trye weight.

∵maximum percentage error = maximum absoulte error/measured value
∴maximum absoulte error = measured value×maximum percentage error
∴maximum absoulte error
= 65×4%
= 2.6 kg
upper limit
= measured value+maximum absoulte error
= (65+2.6)kg
=67.6kg
lower limit
=measured value﹣maximum absoulte error
=(65﹣2.6)kg
= 62.4kg
∴the range of his trye weight is between 62.4kg to 67.6kg .

1)speed=400/60
=6.67m/s(to 3 sig.fig.)
2)65x4%=2.6
thus, range of it =65-2.6to65+2.6
=62.4to67.6(kg)