Question

If Sandra Bullock's speed is incrcased by 2.5 km/hr, then she takes 1/2 hour less to cover 1.5 km. Find her original speed.​

Answer 1

Answer:

1.76 km/h

Step-by-step explanation:

speed= x

Comparing time in both cases:

• 1.5/x-1/2=1.5/(x+2.5)
• (3-x)/2x=1.5/(x+2.5)
• (3-x)(x+2.5)=3x
• 3x+7.5-x²-2.5x-3x=0
• -x²-2.5x+7.5=0
• x²+2.5x-7.5=0

Solving it we get:

• x =(-5+√145)/4= 1.76

Answer: 1.76 km/h