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Significant figures in calculations!?
Solve each of the following math problems and write their answers with the correct number of significant figures.
1. (3.4X8.90) X (2.3+9.002)
2. 1.09X3.498 + 2.45001-2.123/0.0023
Please help, I don't get how to do this.
2 Answers
- 1 decade agoFavorite Answer
Problem 1. Always do the () first.
3.4 x 8.90 = 30
2sf x 3sf = 2sf note the 30 is 2sf even though it ends in 0, because you just determined that.
2.3 + 9.002 = 11.302 = 11.3
1 decimal place + 3 dp = 1 dp
30 x 11.3 = 348 = 350
2sf x 3 sf = 2sf
Problem 2 - since there are no (), you do x/ first, the +- last.
1.09X3.498 + 2.45001-2.123/0.0023
3.81 + 2.45001 - 920 = (-914)
2 dp + 5 dp - 0 dp = 0 dp
Because the last operations are +-, you go by the decimal point, not the fewest sig figs.
Your teacher gave you two problems that took some thinking.
- 1 decade ago
The first one is 300. 1st you multiply 3.4x8.90 and with SIG FIGS you get 30. Next you add 2.3+9.002 and get 11.3. Lastly, you multiply the 2 together and you get 339. But since 30 has 1 SIG FIG, that's how many you are allowed in your answer. So it would be 300.
The second one is -920. Just do order of operations and you should get -916.7806483. Now you have to find the number with the lowest amount of SIG FIGS and that's how many you are allowed in your answer. The smallest number of SIG FIGS is .0023 and that has 2. So, you use those 2 SIG FIGS and should get -920.
