Un alpinist parcurge un traseu montan in 4 zile.In prima zi parcurge jumatate din traseu plus 4 km,in a doua zi parcurge jumatate din rest plus 4 km, iar in a treia zi parcurge jumatate din rest plus 4 km, iar in a patra zi parcurge ultimii 4 km. Calculeaza lungimea traseului parcurs de alpinist in cele 4 zile.
l------------l-l-----------l tot traseul ................4 1 zi l-----l-l----l rest ........4 2 zi l----l-l--l rest ........4 3 zi l--l rest 4 a- 4- zi
4= ( a patra zi) 4+4=8 jumatate 8+4=12 (a treia zi) 8x2=16 16+4=20 rest 20+4=24 (a doua zi) 20x2=40 rest 40+4=44 jumatate 44+4=48 (prima zi) 44x4=88 (tot traseul)
/--------------------------------/----------------/--------/--------/ traseul a=/-----------------------------/+ 4 km b=/---------------/+4 km c=/--------/+4 km d=4 km 4 km+4 km=8 km 8 km+4 km=12 km ( c) 8 km +12km +4 km=24 km (b) 8 km +12 km+24 km+4 km=48 km(a) 48 km+24 km+12 km+4 km=88 km are intreg traseul
