A tree nursery has been experimenting with fertilizer

to increase the growth of seedlings. A sample of

35 two-year-old pine trees is grown for three more

years with a cake of fertilizer buried in the soil near

the trees' roots. A second sample of 35 year-old

pine trees is grown for three more years under

identical conditions (soil, temperature, water) to

the first group, but not fertilized. Tree growth is

measured over the three-year period with the following

results.

Trees with Trees without

Fertilizer Fertilizer

n1 =35 n2 =35

x1 5 97.5 cm x2 5 58.7 cm

O`1 24.9 cm O`2 18.8 cm

Do the data support the theory that the population of

trees with the fertilizer grew significantly larger during

the period in which they were fertilized than the

non-fertilized trees? Use 0.01.