The answer is athe answer is a, although your mouse was in the way so slightly difficult to read
y = 21
i might be wrong, sorry if i am!!
Multiply by 5,280
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The sample mean is approximately normally distributed with mean $75.00 and standard deviation $15.00/sqrt(64)
1) The z-score for $70.00 is
(70 - 75)/(15/8) = -2.66667 = -2.7 to the nearest tenth.
2) The probability corresponding to this z-score is 0.0035 (use standard normal tables), or 0.35%, which rounded to tenths is 0.4%
I will leave the rest to you. The instruction in step 5 is wrong; you do not add the probabilities from steps 1 and 3. (If you do add them, you will get 1, which is clearly the wrong answer.)
P(70 < sample mean < 80) = P(sample mean < 80) - P(sample mean < 70)
so you should subtract the result in step 1 from the result in step 3.
The correct answer is 0.993, or 99.3%
Answer:
3 dimes and 10 quarters
Step-by-step explanation:
If you add 7 dimes, then the number of dimes and quarters is the same, and the total increases to $3.50. A dime and a quarter have a value together of $0.35. Since there are equal numbers, the value $3.50 must be made up of some quantity of groups with a value of $0.35. That number of groups must be ...
... $3.50/$0.35 = 10
Thus, there are 10 quarters and 10-7 = 3 dimes.
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<em>Using an equation</em>
Let q represent the number of quarters. Then the amount Bess has is ...
... 0.10(q -7) +0.25q = 2.80
... 0.35q - 0.70 = 2.80
... 0.35q = 3.50 . . . . . add 0.70 . . . . . . . this should look familiar
... q = 3.50/0.35 = 10