Colors and bugs. What colors attract beetles? The presence of harmful insects in
ID: 3231536 • Letter: C
Question
Colors and bugs. What colors attract beetles? The presence of harmful insects in farm fields is detected by erecting boards covered with a sticky material and then examining the insects trapped on the board. To investigate which colors are most attractive to leaf beetles, ISU researchers placed six boards each of four colors in a field of oats last July. The table below gives data on the number of cereal leaf trapped. At a 1% level (use chart in book), test the belief that the average number of cereal leaf beetles trapped is the same for each of the four colors. Step 1: H_0: _____ H_a: _____ step 2: test statistic: _____ step 3: critical value: ____ step 4: H_0 is accepted/rejected (circle one) step 5: Each of the four colors appear to attract about the same average number of cereal leaf beetles. Yes/No Grand mean: X_GM bar = ____ Between Group Variance: s^2_s = ______ Within Group Variance s^2_w = _______Explanation / Answer
Ho: all colors have same attraction
Ha: at least two of colors have diffeirent color attraction
from above test stat F= 30.552
critical value =4.938
grand mean: 27.292
b/w group variance =1406.153
with in group variance =46.025
step 4: Ho rejected
step 5: no
i ni Xi Si^2 ni*(Xi-mean)^2 (n1-1)*Si^2 lemon 1 6 47.167 46.167 2370.094 230.833333 white 2 6 15.667 11.067 810.844 55.3333333 green 2 6 31.500 98.300 106.260 491.5 blue 3 6 14.833 28.567 931.260 142.833333 mean 27.292 4218.458 920.500 MSG MSE Source of variation SS df MS F P value Fcrit Between groups 4218.458 3 1406.153 30.552 0.00000 4.938193 with in groups 920.500 20 46.025 total 5138.958 23