High School

A girl buys seven pens for #630. How much would 10 pens cost?

A 3-tonne lorry takes 10 trips to move a pile of earth. How many trips would a 5-tonne lorry make?

A 14-year old boy runs 100 m in 14 seconds. How long would it take a 6-year old boy?

A bag of corn can feed 100 chickens for 12 days. For how many days would the same bag feed 80 chickens?

It takes twenty-one 9-l buckets to fill a drum with water. How many 7-l buckets would it take?

A car travels at 60 km/h and takes 5 hours for a journey. How long would the car take, if it travelled at 90 km/h?

A 480-page book is 2.4 cm thick (not counting the thickness of the covers). Find the thickness of 380 pages of the book.

A bag of rice feeds 15 students for 7 days. How long would the same bag feed 10 students?

Five buses need 3 trips to take 450 students to the stadium to watch a concert. How many trips would 3 buses need to take the same number of students?

Answer :

Let's solve each part of the question step by step.

  1. Cost of 10 pens:

    The girl buys 7 pens for #630. So, the cost of one pen is [tex]\frac{630}{7} = 90[/tex] #.

    To find the cost of 10 pens, multiply the cost of one pen by 10:

    [tex]90 \times 10 = 900 \text{ #}[/tex]

    So, 10 pens would cost 900 #.

  2. Trips for a 5-tonne lorry:

    A 3-tonne lorry takes 10 trips. This means a total weight of 30 tonnes is moved. Let's find out how many trips a 5-tonne lorry would take.

    Divide the total weight by the new lorry's capacity:

    [tex]\frac{30}{5} = 6 \text{ trips}[/tex]

  3. Time for a 6-year-old to run 100m:

    Running time depends on factors like age, fitness, etc., but since there isn’t enough information to calculate this, we cannot provide an exact time for the 6-year-old.

  4. Feeding 80 chickens:

    A bag feeds 100 chickens for 12 days. Therefore, the total 'chicken-days' covered is [tex]100 \times 12[/tex].

    For 80 chickens, divide the total 'chicken-days' by 80:

    [tex]\frac{1200}{80} = 15 \text{ days}[/tex]

  5. Filling a drum with 7-litre buckets:

    It takes 21 buckets of 9-litres. So, the drum's capacity is [tex]21 \times 9 = 189 \text{ l}[/tex].

    To see how many 7-litre buckets it takes, divide the drum capacity by 7:

    [tex]\frac{189}{7} = 27 \text{ buckets}[/tex]

  6. Travel time at 90 km/h:

    At 60 km/h, the journey takes 5 hours. Thus, the distance is [tex]60 \times 5 = 300 \text{ km}[/tex].

    At 90 km/h, divide the distance by the new speed:

    [tex]\frac{300}{90} = \frac{10}{3} = 3.33 \text{ hours}[/tex]

  7. Thickness of 380 pages:

    If 480 pages are 2.4 cm thick, the thickness per page is [tex]\frac{2.4}{480} \text{ cm}[/tex].

    Multiply this by 380:

    [tex]\frac{2.4}{480} \times 380 = 1.9 \text{ cm}[/tex]

  8. Feeding 10 students:

    One bag feeds 15 students for 7 days, equivalent to 105 student-days.

    For 10 students, divide by 10:

    [tex]\frac{105}{10} = 10.5 \text{ days}[/tex]

  9. Trips for 3 buses:

    Five buses taking 3 trips handle 15 bus-trips.

    For 3 buses, divide the total by 3:

    [tex]\frac{15}{3} = 5 \text{ trips}[/tex]

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