Answer:
The correct answer is B.12.2
Step-by-step explanation:
Given:
The expression is:

To find:
Part A: The expression using parentheses so that the expression equals 23.
Part B: The expression using parentheses so that the expression equals 3.
Solution:
Part A:
In option A,

[Using BODMAS]

In option B,

[Using BODMAS]

In option C,


In option D,

[Using BODMAS]

After the calculation, we have
and
.
Therefore, the correct options are B and D.
Part B: From part A, it is clear that

Therefore, the correct option is C.
Answer:
The probability that it would take more than four hours to construct a soapbox derby car = 0.1587 or 15.87
Step-by-step explanation:
Given -
Mean
= 3 hours
Standard deviation
= 1 hours
Let X be the no of hours to construct a soapbox derby car
the probability that it would take more than four hours to construct a soapbox derby car =
= 
=
Put 
= 1 -
= 1 - .8413 Using z table
= 0.1587
Use the substitution method
V= s^3
2*2*2= 8 cm^ 3
Answer : 8 cm^ 3 - A