After Reviewing Miriam's Accounting and Business Operations for Her Lunch

After reviewing Miriam's accounting and business operations for her lunch bar,you find that:
• her average figures for sales are based on 3 different lunches:
- a rice dish which sells for $8,of which last year she sold on average 50 per day
- a vegetarian dish which sells for $9,of which last year she sold on average 30 per day
- a meat dish which sells for $10,of which last year she sold on average 20 per day
• the figures were taken from her accounting results for the year from 1 January 20X1 to 31 December 20X1;she does not have results for January-June of the current (20X2)year,as her accountant is still finalising her tax records
• her vegetables and meat are trucked from farms just outside Palmerston North once a week.
a Briefly explain limitations in calculating Miriam's breakeven and target profits relating to the accounting and business operations information above.
b State 2 other external factors that limit the accuracy of Miriam's calculations.