Question

A plane left 20 minutes late due to bad weather and in order to reach its destination 1200 km away, in time , it had to increase its speed by 120 km/h from its usual speed. then the usual speed of the plane is: (A) 500 km/h (B) 450 km/h (c) 600 km/h (D) none of these.

Answer 1

Answer:

(c) 600 km/h

Step-by-step explanation:

Usual speed- x

Distance- 1200 km

Speed increase - 120 km/hr

Time difference- 20 min = 1/3 hr

• 1200/x-1/3=1200/(x+120)
• (3600-x)/3x=1200/(x+120)
• (3600-x)(x+120)=3600x
• 3600x+3600*120-x^2-120x=3600x
• x^2+120x-432000 =0
• x=600

So correct option is (c) 600 km/h

Answer 2

Answer:

here you go,.......

Step-by-step explanation: