Bunuel
In Masonville few streets currently have shade trees. The city's newly adopted goal is to have shade trees on all streets that are wide enough. The trees will cool summer temperatures in the city as well as improve its appearance. Because statistics show that three of every four trees planted in the city die before maturity, the city will plant a tree every ten feet in order to achieve an eventual spacing of 30 to 50 feet between trees.
Which of the following is an assumption on which the city's plan depends?
A. The trees that will be planted as shade trees are hardier and have a greater chance of surviving to maturity than do the trees that have typically been planted in the city in the past.
B. The streets that currently have shade trees are no wider than the streets for which shade-tree plantings are planned.
C. Trees planted in the region of Masonville but outside the city would have a lower mortality rate than trees planted along city streets.
D. The growing conditions do not vary so much from district to district within the city that the mortality rate of trees differs greatly according to the district in which they are planted.
E. Apart from the issue of whether shade trees can be grown, the width of a city street does not contribute to the temperature there on hot summer days.
This is a plan goal type of question.
Goal: To have shade trees on all streets that are wide enough
Plan: Plant a tree every ten feet in order to achieve an eventual spacing of 30 to 50 feet between trees
Additional Details: We are also given some statistical information that three of every four trees planted in the city die before maturity. The plan that was made is assumed to have taken this consideration into account.
A. The trees that will be planted as shade trees are hardier and have a greater chance of surviving to maturity than do the trees that have typically been planted in the city in the past.We don't need to assume this because the plan was made to take into consideration the current survival rate and the current type of trees. Hence, even if the plants have the same trees that will be planted as shade trees have the same survival rate and are of similar type we can arrive at the conclusion. Hence, we can eliminate this option.
B. The streets that currently have shade trees are no wider than the streets for which shade-tree plantings are planned.Well, this information isn't a must-have / must-be true (in other words an assumption) for our conclusion to hold true. We are not given information on what parameters were taken into consideration to formulate the plan. The city officials probably have taken into consideration any differences between the streets in coming up with the plan. Hence, while the difference in width 'may' affect the type of plant that needs to be planted, that information could have been taken into account. Hence, we can eliminate this statement.
C. Trees planted in the region of Masonville but outside the city would have a lower mortality rate than trees planted along city streets.This statement is out of scope. We have to find an assumption in light of the conclusion and the plan made in this question. We can eliminate this option.
D. The growing conditions do not vary so much from district to district within the city that the mortality rate of trees differs greatly according to the district in which they are planted.A good one!
This is an assumption that the city makes. The city in its plan has laid out a decision to have a uniform planting strategy for all the streets. Hence, the city assumes that the planting and survival conditions do not differ greatly. If the survival conditions do differ, the city might need to adopt different strategies to ensure that the plants survive.
We can keep this option.
E. Apart from the issue of whether shade trees can be grown, the width of a city street does not contribute to the temperature there on hot summer days.Not relevant to the conclusion. While there might be other factors at play, the argument at hand is regarding the city's plan to have shade trees on all streets that are wide enough. Hence, we can eliminate E.
This leaves us with D.
Option D