Using the Calculator on the exam!?

January 30, 2020 23:23

Hey All,

Quick question:

I am in Black Spectacles practice exam right now playing around with the resources and getting familiar with using the calculator. I am having trouble understanding how the "log" button works?! This should be so simple yet I can not figure out how to get the correct answer using the calculator.

Im practicing with example problem 19.2 in the Ballast 5.0 book. The questions is:

A room in an office contains eight machines, each of which produces 73dB of sound. What is the overall sound level?

The equation to use is IL(total) = IL(source) + 10log(n) ... so plugging in the numbers from the example problem I get 73dB + 10log(8)

The answer in the book is 82dB.

When I use the calculator and type 73 + 10log8 it only equals 81 ?!?! How to use use the "log" command properly!? Someone please help me solve this silly thing?! I feel like a total idiot.

Comments

5 comments

Kenzie McNamara January 31, 2020 12:53

Following, I had the same issue and even after looking at youtube videos, I don't understand what I'm doing wrong.

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Katie Merten January 31, 2020 13:50

This is likely an error in the book and you are using the function correctly. If not, I, too, am going crazy.

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Peter Mall February 03, 2020 18:21

I cam across this recently in my studies, but it didn't cause me to flinch. I'm not sure what you are doing wrong, make sure you are closing parentheses correctly (some calculators don't follow the order of operations correctly). If all else fails, check your work on Google.

log(8) = 0.903

10 * log(8) = 9.03

73 + 10 * log(8) = 82.03

the answer is 82 dB

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Kenzie McNamara February 03, 2020 21:19 (Edited February 03, 2020 21:19)

I put it in the calculator wrong. I kept typing 10Log then (8) which was giving me an error. It is actually supposed to be typed

Log8 then multiply it by 10.

Thank you Peter!

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Joseph Petrarca August 01, 2020 15:06

The calculator sucks. I'm used to a Hewlett Packard 32 which I've been using for over thirty years. When you are used to the RPN, this drugstore calculator seems like Fisher Price.

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