It has been shown that the fertilizer magnesium ammonium phosphate, MgNH4PO4, is an effective supplier of the

Question:

It has been shown that the fertilizer magnesium ammonium phosphate, MgNH4PO4, is an effective supplier of the nutrients necessary for plant growth. The compounds supplied by this fertilizer are highly soluble in water, allowing the fertilizer to be applied directly on the soil surface or mixed with the growth substrate during the potting process. A study on the Effect, of Magnesium Ammonium Phosphate on Height of Chrysanthemums was conducted at George Mason University to determine a possible optimum level of fertilization, based on the enhanced vertical growth response of the chrysanthemums. Forty chrysanthemum seedlings were divided into 4 groups each containing 10 plants. Each was planted in a similar pot containing a uniform growth medium. To each group of plants an increasing concentration of .MgNH4PO4, measured in grains per bushel, was added. The 4 groups of plants were grown under uniform conditions in a greenhouse for a period of four weeks. The treatments and the respective changes in heights, measured in centimeters, are shown in the following table:

Can wc conclude at the 0.05 level of significance that different concentrations of Mg'NH.iPO.i affect the average attained height of chrysanthemums'' How much Mg'NH.iPO.i appears to be best?