5% x500+(x-500)x 10% = 120
25+0. 1x-50= 120
0. 1x= 145
x= 1450
2000+ 1450=3450 (yuan)
2. Solution: Let the bottom radius be r decimeter.
2RX3. 14+2R= 12.42
8.28R= 12.42
R= 1.5
Bucket height: 1.5X2=3 (decimeter)
Volume:1.5x1.5x3.14x3 = 2 1.195 (liter) is approximately equal to 21liter.
3. Solution: If X people are unqualified, then 3x+4 people are qualified.
3x+4+5=6(x-5)
3x+9=6x-30
3x=39
x= 13
3X 13+4+ 13=56 (person)