reliability of the estimates

starting bit is about directors proposing to sell their 25% shares to raise $1M and then there is statement of financial position ,after that its this
Additional information
(i) The average price earnings ratio of AIM listed companies in the same industry as
Grant is 8.33, and average earnings per share is 20 cents.
(ii) The value of freehold land and buildings (never revalued) has fallen by 25% since
purchased due to a recession.
(iii) The replacement cost of plant and equipment is $1,500,000 but its current realisable value
is $1,125,000.
(iv) $180,000 of inventory is obsolete and could only be sold for $10,000 as scrap.
Required:
Estimate the value of a share in Grant and Co using:
(i) a suitable PE ratio
(ii) an asset based value.
Comment on the reliability of your estimates.

I can estimate the value , no problem , but the bit about the reliability of the estimates ,so its about the estimated P.E ratio since its average it cant be accurate and the asset based value the decrease in land building is 25 % which is entirely subjective , but since comments are for 7 marks what more can i add ?