Round , absolute and relative error

Hi all,

i have find this exercise in internet and try solve it but cant, pls help me.

Thanks

1.Given A = 3.9 after rounding. Find the range of real value for A before rounding if A has been round to

(i) 1 decimal places.

(ii) 2 significant figures

2.If *x* = 2.0, *y* = 3.0 and *z* = 4.0, all are corrected to 1 decimal places, calculate the absolute and relative error for

(i) 2*x* + *y*

* (ii) $\displaystyle \frac{x+z}{y}$*

3.The position of nine trees which are to be planted a long the sides of a road, five on the north side and four on the south side.

If there are 3 figs, 4 prunes and 2 magnolias, find the number of different ways in which these could be planted assuming that the trees of the same species are identical.