[填空题]
Elon is challenged to a speed climb at a l* d7.2vctgwem1oa f,h ocal mountain. He has to reax0:vz i- rs9rbch a height of:x0rs-bz irv9 400 metres above the ground within four hours.
Elon knows he can climb 150 metres in the first hour. Due to increasing tiredness, each hour he can only climb 75% of the height climbed in the previous hour.
1.Verify that Elon reaches his target height of 400 metres in four hours.
$S_4$≈ m
The mountain has a height of 650 metres. Elon decides to attempt to climb to the summit.
2.Determine whether he can reach the summit of the mountain if he continues climbing, given his increasing tiredness. Justify your answer.
$S_∞$= m
On a different day, Elon climbs with energy snacks, which help to reduce his tiredness as he climbs. On this day, Elon again climbs 150 metres in the first hour, but then k% of the height he climbed in the previous hour, where k>75.
3.Calculate the minimum value of k, given that on this day Elon is able to reach the summit. Give your answer as a percentage, to the nearest whole number.
The minimum value of k is %
