Answer:
75%
Explanation:
In order to understand this question you need to understand the matching law first. The matching law provides the density of reinforcement or the rate of reinforcement if more than one response is available simultaneously to the individual. Here, two responses are available which are left key, 60 reinforcers per hour, and right key, 20 reinforcers per hour. This provides the ratio between the two reinforcers which is 60:20 or 3:1 in favor of left key. Here, one has to make a prediction only for left key and based on 3:1 ratio it can be said that 75% of pigeon will make their responses on the left key.
A cause and effect due to process of elimination and the text
Trades.
For example; the trade of wheat, other cash crops and natural resources
By appointing Abraham Lincoln to run against Stephen Douglas in the senate race.
