F.2 mathz(easy calculate)

1)Calculate the following,correct your answer to 2 sig.fig.
a)1.78x2.01
=3.5778
=3.6(correct to 2 sig.fig.)
b)61/21.4
=2.9(correct to 2 sig.fig.)
2)The figure shows a stamp with dimension 22mmx28mm.
a)Find the area of the stamp to the nearest cm^2.
the area of the stamp
= 22mmx28mm
=2.2cm x 2.8cm
=6.16cm^2
=6cm^2(correct to the nearest cm^2)
b)A sheet of stamps contains 200stamps.Find the area of the sheet of stamps to the nearest cm^2.
the area of the sheet of stamps
=20(6.16cm^2)
=123.2cm^2
=123cm^2(correct to the nearest cm^2)
3)The length of a road is 28.3km.
a)How many sig.fig. is it?
3
b)Find the upper limit and lower limit of the length.
the maximum absolute error
=1/2 * (0.1)
=0.05km
the upper limit of the length
=28.3+0.05
=28.35km
the lower limit of the length
=28.3-0.05
=28.25km