A Study of the Effects of a Chemical Additive on Soil

question 73

Multiple Choice

A study of the effects of a chemical additive on soil acidity recorded the acidity of eight plots of land before and after the application of the additive. The results were:

$\begin{array}{|l|l|l|l|l|l|l|l|l|}\hline \text { Plot } & 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 \\\hline \text { Before } & 10 & 8 & 9 & 7 & 8 & 6 & 9 & 11 \\\hline \text { After } & 8 & 7 & 7 & 8 & 6 & 6 & 8 & 8 \\\hline & & & & & & & & \\\hline\end{array}$


The test value for the signed-rank test is:

• A) 1
• B) 2
• C) 3
• D) 4

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Definitions:

Suicide

Purposefully causing one's own demise.

Lithium

A chemical element and mood-stabilizing drug used to treat mood disorders, such as bipolar disorder.

Neuron

A specialized cell transmitting nerve impulses; a nerve cell.

Neurotransmitter

Chemical substances in the nervous system that transmit signals across synapses from one neuron to another.