## Tuesday, July 7, 2009

### Practice for test 7/7

A) A rock concert registers at about 105 decibels and a jet engine at 140 decibels. How many more times the energy is produced by the engine compared to the speakers at the concert?

Use the order of operations to get a single number from these mathematical terms. If the answer is not a whole number, round to two places after the decimal.

Note: sqrt(...) means square root, / means division, ^ means exponentiation and * mean multiplication.

B) sqrt(7^2 + 1^2)

C) 8 - 4
__12-(-8)

D) 3(5+2) - 4/6*15 + 8(3/2)

#### 1 comment:

Prof. Hubbard said...

A) A rock concert registers at about 105 decibels and a jet engine at 140 decibels. How many more times the energy is produced by the engine compared to the speakers at the concert?

Answer: 140-105 = 35 decibels = 3.5 bels.

10^3.5 = 3,162.27, so the jet engine produces over 3,000 times more energy than the rock concert.

Use the order of operations to get a single number from these mathematical terms. If the answer is not a whole number, round to two places after the decimal.

B) sqrt(7^2 + 1^2)

Answer: sqrt(49+1) = sqrt(50) ~= 7.07

C) (8 - 4)/(12-(-8)) = 4/20 = 1/5 = .2

D) 3(5+2) - 4/6*15 + 8(3/2)

3*7 - 4/6*15 + 8*3/2 =

21 - 10 + 12 =

11 + 12 = 23