Answers for "Calculate This!" activity

Here is the activity without the answers:
Here is the activity with answers:
The 1,500,000 Mexican free-tailed bats in the Selman Cave bat colony in Oklahoma eat a huge number of insects during the months they live there. These insects include crop pests, such as Corn Ear Worm moth and the Cucumber Beetle, that cost American farmers over $14,000,000,000 ($14 billion) each year. A Mexican free-tailed bat eats up to 10 grams of insects in a night, so... 


  1. How many grams of insects does the Selman Cave bat colony eat in one night?

            10grams*1500000bats= 15000000grams

  1. How many pounds of insects is that?  1 gram=.0024 pounds

            15000000grams*.0024 lbs=33600lbs of insects a night!


Farm Journal reported on a 2016 research project by Josiah Maines at Southern Illinois University Carbondale, in which bats were shown to save farmers $74 per acre in crop pest control.  The average Oklahoma farm is 438 acres and there are over 78,000 farms in the state.


  1. How much do bats save the average Oklahoma farmer each year?

            $74/acre*438 acres= $32,412.00 

  1. How many dollars do bats save farmers across the state of Oklahoma each year?

            $32,412.00*78,000 farms= 2,528,136,000 over 2 and a half billion dollars a year!!!

The average annual cost of attending the University of Oklahoma is $10,090

The average Oklahoma farm costs $486,180 to buy.  

  1. What do you think?  Is it worth it for the average Oklahoma farmer to protect bats?  Include a reason for your answer.