Handy hiking produces backpacks. in 2007, its highest and lowest production levels occurred in july and january, respectively. in july, it produced 4,000 backpacks at a total cost of $110,000. in january, it produced 2,500 backpacks at a total cost of $87,500. using the high/low method, the average variable cost of producing a backpack was:

The average variable cost of producing a backpack is $15.

The formula for calculating the variable cost per unit using the high/low method is:

where

y₂  : cost at highest level of activity

y₁  : cost at lowest level of activity

x₂  : number of units produced at highest level of activity

x₁  : number of units produced at lowest level of activity

Substituting the values from the question in the formula we get,

ans.

heterothermic organisms include those organisms that can switch between homeothermic (having body temperature higher than environment) and poikilothermic (having variation in internal body temperature) strategies.

some migratory birds show heterothermy as they decrease their metabolic rate during cold nights to keep their body temperature low. drop in metabolic rate allows increase in production efficiency of birds that reduces the internal body temperature to make it equal to external cold temperature during cold nights.

thus, the correct answer is 'birds allow their temperature drop in order to increase their production efficiency.'