Explanation

Explanation

Given Information:

• A lifter loads 200 packages per hour.
• A labor loads two quarters (i.e., 2/4 or 1/2) less than 200 packages per hour.
  • 1​/2×200=100
  • So, the labor loads 200 - 100 = 100 packages per hour.
• Together, the lifter and labor load:
  $$200+100=300\text{ packages per hour}$$
• They need to load 1500 packages.
• They take 30 minutes (0.5 hours) rest after every 2 hours of loading.

Step 1: Calculate Total Loading Time Without Breaks

1500/300​=5 hours

So, if they were working continuously, they would need exactly 5 hours.

Step 2: Account for Breaks

• They work for 2 hours, then take a 30-minute (0.5-hour) break.
• In 2 hours, they load:
  $$2\times 300=600\text{ packages}$$
• After 2 hours, they take a 0.5-hour break.
• Continuing this cycle:
  • First 2 hours: 600 packages (then a 30-minute break)
  • Next 2 hours: 600 packages (then a 30-minute break)
  • Remaining: 300 packages, which takes 1 more hour (no need for another break).

Total time including breaks:

$$2+0.5+2+0.5+1=5.5\text{ hours}$$

Step 3: Select the Correct Answer

$$(\mathbf{b})5.5\text{ hours}$$

Explanation

If you were born in 1945 and it's now 1965, you can calculate your age by subtracting your birth year from the current year:

Age = Current Year - Birth Year

Age = 1965 - 1945

Age = 20

So, if you were born in 1945, you would be 20 years old in 1965.

Explanation

Explanation

To solve the problem, follow these steps:

1: Determine B's efficiency compared to A:

• A can finish the work in 40 days, so A's work rate is  1/40 of the work per day.
  
• If B is 255% less efficient than A, it means B's efficiency is reduced by 255%, which implies B is not practically effective (usually considered inefficient or not working effectively in real terms).

2: Calculate B's efficiency:

• If B is 255% less efficient, B's effective efficiency would be negative, which isn't practically feasible. To make sense of this:
• Assume B’s efficiency is effectively lower compared to A in realistic scenarios.

3: Adjust B's effective efficiency for practical calculations:

• Let's use a model where B is significantly less efficient but not zero. For instance, if B’s efficiency is assumed to be around 10% of A’s for simplicity:
• B can do the work in approximately 400 days.

The closest feasible answer given practical scenarios and combined work rate calculations is None.

Explanation

Work = Men × Days = 120 × 30 = 3600 man-days

If 80 men work: 3600 ÷ 80 = 45 days

Explanation

Total students = 35 → Total height = 35 × 161 = 5635 cm

14 girls = 14 × 151 = 2114 cm

So, 15 girls = (2114 + x) → x = height of 1 girl = assume x = 151

Total height of 15 girls ≈ 15 × 151 = 2265

Total height of boys = 5635 - 2265 = 3370

Mean height of 20 boys = 3370 ÷ 20 = 169 cm

Explanation

Speed=150 m​/15 s=10 m/s

Explanation

Let's break down the movements step by step:

East 10 meters:

You are now 10 meters east of your house from the starting point.

North 15 meters:

Now you're 10 meters east and 15 meters north of your house.

West 12 meters:

Moving west by 12 meters puts you 2 meters west of your house (because 12 - 10 = 2).

South 15 meters:

Moving south 15 meters brings you back to your house's north-south position (because 15 meters north - 15 meters south = 0).

So now you're 2 meters west and 0 meters north-south from your house.

The distance from your house is simply 2 meters.

Explanation

"One quarter past 3" means 15 minutes after 3 o'clock.