15. Before oil is added to a certain road surface material, the other ingredients are mixed. The mixture contains
1 answer:
Answer:
sand = 3450 pounds
3/4 inch stones =6750 pounds
1 inch stones =4800 pounds.
Step-by-step explanation:
The mixture composition is :
45% three-quarter inch stones
32% inch stones and
sand for balance
The percent here is by mass of material used.
Weight of mixture is 15,000 pounds before oil addition.
Use the percent by weight for the two types of stones and calculate real values in pounds
Formula to apply is:
Mass percent = (mass of a material/ total mass of mixture) * 100
For 3/4 inch stones it will be:
The 3/4 inch stones weigh 6750 pounds
The 1 inch stones will be
The 1 inch stones weigh = 4800 pounds
Total for the two items : 4800+6750 =11550 pounds
The sand used weighs : 15000 - 11550 = 3450 pounds
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Using the normal distribution, it is found that 63.18% of the area under the curve of the standard normal distribution is between z = − 0.9 z = - 0.9.
<h3>Normal Probability Distribution</h3>The z-score of a measure X of a normally distributed variable with mean and standard deviation
is given by:
- The z-score measures how many standard deviations the measure is above or below the mean.
- Looking at the z-score table, the p-value associated with this z-score is found, which is the percentile of X.
The area within 0.9 standard deviations of the mean is the <u>p-value of Z = 0.9(0.8159) subtracted by the p-value of Z = -0.9(0.1841)</u>, hence:
0.8159 - 0.1841 = 0.6318 = 63.18%.
More can be learned about the normal distribution at brainly.com/question/4079902
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