Question

how to Solve 2.5×9.8×20÷1.25×10 raise to -4 × 10 raise to -4​

Answer 1

Explanation:

Let, v Kmh-1 = constant speed with which the buses ply between the towns A and B.

Relative velocity of the bus (for motion A to B) w.r.t. the cyclist (i.e. in the direction in which the cyclist is going = (v – 20) kmh-1

Relative velocity of the bus (for motion B to A) w.r.t. the cyclist = (v + 20) kmh-1

The distance travelled by the bus in time T (minutes) = vT

As per question, vT /(v – 20) = 18, or, vT = 18v – 18 × 20 … (i)

and, vT/(v + 20) = 6, or, vT = 6v + 20 × 6 … (ii)

Solving (i) and (ii), we get, v = 40 kmh-1

Putting this value of v in (i) we get,

40T = 18 × 40 – 18 × 20 = 18 × 20 or, T = 9 mins.

Answer 2

Answer:

0.00000392

=2.5 × 9.8 = 24.5

=24.5 × 20 = 490

=490 ×1.25 = 392

=392 × 10-⁴ = 0.0392

=0.0392 × 10-⁴ = 0.00000392