Reschayu, a tolku nikakogo!!!!! :cry:

Reschenie :

truba 1 ( 4 chasa=4*60 = 240 min)
truba 2 ( 2 chasa=2*60=120 min)
truba 3 ( 1 chas = 60 min)

-truba 1 sa pervie 10 min (rabotaya odna) napolnit
1/240 * 10=1/24 basseina

Sleduschie 30 min rabotajut truba1 i truba 2 vmeste :
1/240*30 + 1/120*30 = 1/8+1/4=3/8 basseina sapolneno

=> VSEGO use sapolnilos 1/24+3/8=10/24=5/12

Teper' vkluchilas tret'ya truba... A sapolnit' ostalos :
1-5/12 = 7/12 basseina.

S tremja trubami, poluchaetsja :

(7/12)/240 + (7/12)/120 +(7/12)/60=(7/12)/x

x=240/7 (min) = 4/7 (chasa)

40 min = 4/6=2/3 (chasa)

4/7 +2/3 = 26/21 :evil: :evil: :evil: :evil: gde oschibka :?:

Reschayu, a tolku nikakogo!!!!! :cry:

Reschenie :

truba 1 ( 4 chasa=4*60 = 240 min)
truba 2 ( 2 chasa=2*60=120 min)
truba 3 ( 1 chas = 60 min)

-truba 1 sa pervie 10 min (rabotaya odna) napolnit
1/240 * 10=1/24 basseina

Sleduschie 30 min rabotajut truba1 i truba 2 vmeste :
1/240*30 + 1/120*30 = 1/8+1/4=3/8 basseina sapolneno

=> VSEGO use sapolnilos 1/24+3/8=10/24=5/12

Teper' vkluchilas tret'ya truba... A sapolnit' ostalos :
1-5/12 = 7/12 basseina.

S tremja trubami, poluchaetsja :

(7/12)/240 + (7/12)/120 +(7/12)/60=(7/12)/x

x=240/7 (min) = 4/7 (chasa)

40 min = 4/6=2/3 (chasa)

4/7 +2/3 = 26/21 :evil: :evil: :evil: :evil: gde oschibka :?: