[Punith]

To solve this problem, we need to determine how long it takes for the car to cover a distance of 345 km by gradually increasing its speed every 2 hours.

Let’s break down the problem into intervals and calculate the time taken for each interval.

Interval 1:

Initial speed = 70 km/hr

Time taken = 2 hours

Distance covered = Speed × Time = 70 km/hr × 2 hr = 140 km

Interval 2:

Speed after 2 hours = 70 km/hr + 10 km/hr = 80 km/hr

Time taken = 2 hours

Distance covered = Speed × Time = 80 km/hr × 2 hr = 160 km

Interval 3:

Speed after 4 hours = 80 km/hr + 10 km/hr = 90 km/hr

Time taken = 2 hours

Distance covered = Speed × Time = 90 km/hr × 2 hr = 180 km

Total distance covered in the above intervals = 140 km + 160 km + 180 km = 480 km

Now, we need to determine how much time is needed to cover the remaining distance of 345 km (480 km – 345 km = 135 km) with a constant speed of 90 km/hr.

Time taken for the remaining distance = Distance / Speed = 135 km / 90 km/hr = 1.5 hours

Adding the time taken for the intervals and the remaining distance, we get:

Total time taken = 2 hours + 2 hours + 2 hours + 1.5 hours = 7.5 hours

Converting 0.5 hours into minutes, we have 0.5 hours × 60 minutes/hour = 30 minutes.

Therefore, the car will cover 345 km in 7 hours and 30 minutes.

The closest option to this answer is (b) 4 hr 5 min.

[Punith]

To calculate the volume of a rectangular prism, you multiply its length, width, and height. Similarly, to find the total surface area, you need to calculate the sum of the areas of all its faces. Let’s calculate them step by step:

Volume:

The formula for volume is V = length × width × height.

Given:

Length = 8 cm

Width = 5 cm

Height = 3 cm

V = 8 cm × 5 cm × 3 cm

V = 120 cm³

Therefore, the volume of the rectangular prism is 120 cubic centimeters (cm³).

Total Surface Area:

The formula for the total surface area is A = 2lw + 2lh + 2wh, where l is the length, w is the width, and h is the height.

Given:

Length = 8 cm

Width = 5 cm

Height = 3 cm

A = 2(8 cm × 5 cm) + 2(8 cm × 3 cm) + 2(5 cm × 3 cm)

A = 2(40 cm²) + 2(24 cm²) + 2(15 cm²)

A = 80 cm² + 48 cm² + 30 cm²

A = 158 cm²

Therefore, the total surface area of the rectangular prism is 158 square centimeters (cm²).

So, the volume of the rectangular prism is 120 cm³, and the total surface area is 158 cm².