Question

Starting on Sunday, each day Sania cycled twice as far as the day before for a whole week. If she cycled 3⁄4 km on Sunday, on which day did she first cycle over 15 km? ​

Answer 1

Ok now first see how many days it will take to reach 12
3/4 x 2^4 = 12
So 4 days I.e Thursday
So clearly on Friday she will cycle over 15km (24km)

Answer 2

Given: Starting on Sunday, each day Sania cycled twice as far as the day before for a whole week.

She cycled 3⁄4 km on Sunday.

To find: The day on which she first cycled over 15 km

Solution: We see that Sania cycles 3/4 km on Sunday.

According to the question,

On Monday, she cycled = 3/4 × 2 km = 3/2 km.

On Tuesday, she cycled = 3/2 × 2 km = 3 km.

On Wednesday, she cycled = 3 × 2 km = 6 km.

On Thursday, she cycled = 6 × 2 km = 12 km.

On Friday, she cycled = 12 × 2 km = 24 km.

Therefore, the day on which she first cycled over 15 km is Friday.

Answer: Friday