The iron cube of side 42 com has a hole of diameter 14cm
1 answer:
Answer:
Step-by-step explanation:
Total surface of the cube = 6a²
= 6 * 42 * 42
= 10584 cm²
Hole that is drilled out, will make a cylinder shape in the middle of the cube
Volume of iron in the cube = Volume of cube - volume of cylinder
Volume of cube = a³
= 42 * 42 * 42
= 74088 cm³
Cylinder:
r = 14/2 = 7 cm
h = sideof the cube = 42 cm
Volume = πr²h
= 6468 cm³
Volume of iron in the cube = Volume of cube - volume of cylinder
= 74088 - 6468
= 67620 cm³
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Answer:
a) The probability that Jodi scores 78% or lower on a 100-question test is 4%.
b) The probability that Jodi scores 78% or lower on a 250-question test is 0.023%.
Step-by-step explanation:
a) To approximate this distribution we have to calculate the mean and the standard distribution.
The mean is the proportion p=0.85.
The standard deviation can be calculates as:
To calculate the probability that Jodi scores 78% or less on a 100-question test, we first calculate the z-value:
The probability for this value of z is
The probability that Jodi scores 78% or lower on a 100-question test is 4%.
b) In this case, the number of questions is 250, so the standard deviation needs to be calculated again:
To calculate the probability that Jodi scores 78% or less on a 250-question test, we first calculate the z-value:
The probability for this value of z is
The probability that Jodi scores 78% or lower on a 250-question test is 0.023%.