Answer to Question #173591 in Statistics and Probability for ANJU JAYACHANDRAN

Question

5b) It is desired to estimate average annual wool yield per sheep for a herd of 150 at a

certain farm house using stratified simple random sampling. Sheeps in the herd are to

be grouped into three strata on the basis of first shaving in days. Optimum method

sample allocation is said to be used for selecting the overall sample of 25 sheeps

from the three strata. Determine approximately optimum strata boundaries using the

information on first shaving given below.

Shaving days No. of Sheep 

)f(

f

 30-70 6 2⋅ 45

70-110 2 1⋅414

110-150 1 1 

150-190 4 2 

190-230 2 1⋅414

230-270 7 2⋅646

270-310 8 2⋅828

310-350 20 4⋅ 472

350-390 10 3⋅162

390-430 25 5 

430-470 40 6⋅325

470-510 25 5

Answer 1

Given data is-

The sample has already divided into 9 stratas based on annual wool yield per sheep.

To create 3 strata, we merge the first 3, next 3 and last 3 given strata i.e. 

Note: Strata are constructed such that they are non-overlapping and homogeneous with the character under study.