1)A hawker bought 750 eggs, 25 of them were broken. Find the percentage of eggs that were broken.
2) Peter claims that when a number x is increased by 10%, thevalue of x is unchanged.
His calculation: x(1=10%-10%)=x
Pter is wrong. Point out the mistake.
3) hence find 1+2+3...+1000=?
maths 問題 急 急 急
2007-09-04 4:27 am
回答 (3)
2007-09-04 4:34 am
✔ 最佳答案
1. The percentage of eggs that were broken:= 25 / 750 x 100%
= 10/3 % (Or 3.3333333333333 ... %)
2. The new value of x:
= x (1 + 10%)
= 1.1x≠x
3. 1 + 2 + 3 + ... + 1000
= (1 + 1000) x 1000 / 2
= 1001 x 500
= 500500
2007-09-04 4:35 am
1) 25/750 * 100% = 3.33%
2) I think the question should be:
Peter claims that when a number x is increased by 10% and then decreased by 10%, the value of x is unchanged.
x(1+10%)(1-10%)
=x(1.1)(.9)
= .99x
3) 1+2+3+...+1000
=(1 + 1000)x1000/2
= 500500
2) I think the question should be:
Peter claims that when a number x is increased by 10% and then decreased by 10%, the value of x is unchanged.
x(1+10%)(1-10%)
=x(1.1)(.9)
= .99x
3) 1+2+3+...+1000
=(1 + 1000)x1000/2
= 500500
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