Let the distance traveled be x km.
Then, x/10 - x/15 = 2
3x - 2x = 60 => x = 60 km.
Time taken to travel 60 km at 10 km/hr = 60/10 = 6 hrs.
So, Robert started 6 hours before 2. p.m. i.e., at 8 a.m.
Required speed = 60/5 = 12 kmph.

Speed of the train relative to man = (125/10) m/sec = (25/2) m/sec.
[(25/2) x (18/5)] km/hr = 45 km/hr.
Let the speed of the train be 'S' km/hr.
Then, relative speed = (S - 5) km/hr.
S - 5 = 45 => S = 50 km/hr.

The construction of the world’s largest optical telescope has started in northern Chile, which is expected to begin operating in 2024. The Extremely Large Telescope (ELT) is being built by the European Southern Observatory (ESO) and will have a main mirror that is 39m in diameter. The telescope will be positioned on top of Cerro Armazones – a 3046-metre long mountain Chile. It will tackle a wide range of scientific challenges, including probing Earth-like exoplanets for signs of life, studying the nature of dark energy and dark matter, and observing the universe’s early stages to explore humans’ origins.

Residents of Vadodara, the 10th cleanest city in the country has created a new Guinness world record with maximum number of people sweeping the ‘floor’ (single venue). Vadodara municipal corporation commissioner Vinod Rao said around 5,058 people came together to sweep the venue – a bridge connecting Akota with Dandia bazaar – spread over one kilometre. The record was achieved by participants who swept the place in groups of 50.

Lowest 4-digit number is 1000.
LCM of 3, 4 and 5 is 60.
Dividing 1000 by 60, we get the remainder 40. Thus, the lowest 4-digit number that exactly divisible by 3, 4 and 5 is 1000 + (60 - 40) = 1020.
Now, add the remainder 2 that's required. Thus, the answer is 1022.

6M + 3B = 4(1M + 1B)
6M + 3B = 4M + 4B
2M = 1B

M/B = 1/2

Mumbai has been ranked the world's second most densely populated city with 31,700 people per sq km, by the World Economic Forum (WEF) citing UN Habitat Data. Bangladesh's capital Dhaka topped the list with 44,500 people per sq km. Rajasthan's Kota has been ranked the world's seventh most densely populated city with 12,100 people per sq km.