✔ 最佳答案
1. Jim measured the weight of an apple to be 31.8g. If the actual weight of the apple is 32g, find the percentage error of Jim's measurement.
(difference between measured value and actual value)/actual value x 100%
= (32 kg – 31.8 kg)/32 kg x 100% = 0.2 kg/32kg x 100% = 0.625%
2. Express the following no. in scientific notation :
450 000 000 = 4.5 x 100000000 = 4.5 x 10^8
287.1 = 2.81 x 100 = 2.81 x 10^2
0.000237 = 238/1000000 = 2.38 x 100/1000000 = 2.38/10000 = 2.37 x 10^-4
0.00305 = 305/100000 = 3.05 x 100/100000 = 3.05/1000 = 3.05 x 10^-3
129 x 1000 = 129000 = 1.29 x 100000 = 1.29 x 10^5
1 967 000 = 1.967 x 1000000 = 1.967 x 10^6
3 120 000 = 3.12 x 1000000 = 3.12 x 10^6
3. what is the maximum absolute error, relative error and % error
of 2.50 km ?
give the ans. corr. to 3 sig. fig.
This question is incomplete. Some data are missing!
4. A queation of linear equations in two unknowns :
which of the following cannot form a straight line ?
A. x=3 (vertical line)
B. y=4 (horizontal line)
C. x-3=y (linear equation)
D. 4xy=8 (reciprocal equation)
D. 4xy = 8 cannot form a straight line.
4xy = 8 is same as y =2/x This is a reciprocal equation.
For linear equation y = mx + b where m and b must be real number.
For horizontal line y = b
For vertical line, x = a (a is a real number)
2011-08-31 09:36:14 補充：
scientific notation:
a x 10^n (a must be 1 <= a < 10, n is an integer)
129000. 1.29000
定點位從三個零後面移去1後面, 向左邊移了5個位
所以 1.29 x 10^5
0.00305 0003.05
定點位從第一個零後面移去3後面, 向右邊移了3個位
所以 3.05 x 10^-3
少過 1, 10是 raised to a negative integer.
多過 10,10是raised to a positive integer.
2011-09-03 02:58:47 補充：
Sorry, 在Question 1, unit 是 g (gram),我寫了kg (kilogram),unit cancel out, 答案仍然是 0.625%
0.2 g/32g x 100% = 0.625%
2011-09-03 03:13:31 補充：
Common sense tells anyone that an apple cannot weigh 32 kg! I had to be sleepy.
2011-09-03 09:02:04 補充：
Absolute error is |measured value - true value|. In question 3, we only have 2.50 km. measured value or true value ? Can't find absolute error an relative error.
You may assume 2.50 km +-0.01 km. Maximum absolute error is 0.01 km and relative error is 0.01km/2.50 km = 0.004 or 0.4%
2011-09-03 09:44:58 補充：
For question 3,
If you take certain assumption, maximum absolute error is 0.01 km and relative error is 0.01km/2.50 km = 0.004 and % error = 0.4%
run out of space, go to 意見
2011-09-13 05:23:44 補充：
To 回答者:STY™:
No offence:
Question 1:
0.2g/32g x 100% is not equal to 62.5%
Question 2:
max. absolute error = 0.01 / 2 km = 0.005 km
Where does 2 km come from in the above statement?
