In a field of barley the grain, y_i, and the grain plus straw, x_i, were weighted for each of a large number of sampling units located at random over the field. the total produce (grain plus straw) of the whole field was also weighed. the following data were obtained: c_yy = 1.13, c_yx = 0.78, c_xx = 1.11. compute the gain in precision by estimating the grain yield of the field from the ratio of grain to produce instead of from the mean yield of grain unit. it requires 20 min to cut, thresh, and weigh the grain on each unit, 2 min to weigh the straw on each unit, and 2 hr to collect and weigh the total produce of the field. how many units must be taken per field in order that the ratio estimate may be more economical than the mean per unit?

(d)

step-by-step explanation:

given: the line in the graph passes through points (5,30) and (6,26).

then, the equation of line is:

now, put y=a(n) and x=n,

hence, option d is correct.

step-by-step explanation:

mark other person brainliest

option a is correct.

step-by-step explanation:

scale factor: it is used to find proportional measurements.

proportions means having the same ratio.

scale factor is the ratio of the model measurement to the actual measurement in a simplest form.

or we can say that the ratio of any two corresponding lengths in two similar geometric figures

if the scale factor is more than 1, then it is an enlargement,

if the scale factor less than 1, then it is a reduction.

given the two geometric figure:

by definition of proportions, we have