Answer:
E) An observational study using a stratified sample.
Step-by-step explanation:
This study is not an experiment because the customers were not subjected to any treatment but just observation from those selected. Also, the sampling method used was stratified sampling because we see that random samples were selected independently from two unique populations which are population of those that purchased computers and those that offer tech support.
Therefore the correct option is E.
Well if you set the equation equal to zero X will equal negative 4 so if you take your other answer choices and equal them to zero whichever one x equals negative 4 that's your answer
9514 1404 393
Answer:
cos(A) ≈ 0.9165
Step-by-step explanation:
Put the given value into the given relation and solve for the unknown.
sin²(A) +cos²(A) = 1
(2/5)² + cos²(A) = 1
cos²(A) = 1 -4/25 = 21/25 . . . . . subtract (2/5)²
cos(A) = √(21/25) ≈ 0.9165 . . . . . take the square root
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Both sine and cosine are positive in Quadrant I, so we're only interested in the positive square root.
The absolute value is 10/7
