3. [Maximum mark: 8]
At a horticulture lab, the sizes of Malus Domestica, (a type of apple) are studied to determine the effectiveness of the new fertilizer "GeoGrowth", in increasing the size of apples compared to the original fertilizer, "A Grade Fertilizer". In a 200 m² yard, 20 apple trees are planted in two separate areas, 10 fertilized with "GeoGrowth", and 10 fertilized with "A Grade Fertilizer".
At the time of harvesting, the researchers at the lab collected apples at random from each tree and measured their diameters in cm. The data are shown below.
(new) Geogrowth, cm: 8.4, 8.0, 7.6, 7.9, 6.8, 7.2, 7.7, 8.1, 7.5, 7.1
(orig) A Grade Fertilizer, cm: 6.5, 7.1, 7.4, 6.9, 7.5, 6.6, 7.0, 8.1, 6.3, 7.3
A t-test is performed at the 5% significance level. Both samples are assumed to be normally distributed with equal variances.
a. Write down the null and alternative hypothesis for the test.
b. Draw a diagram of the distribution that reflects this test.
c. Find the t value and p value for the test.
d. State the conclusion of the test. Justify your answer.